Mask producing method

ABSTRACT

A pattern region of a working reticle is divided into existing pattern portions and newly-forming pattern portions. With respect to the existing pattern portions, already-formed master reticle patterns are reduction-projected while stitching screens using an optical-type projection exposure apparatus. With respect to the newly-forming portions, enlarged patterns are formed by an electron beam drawing apparatus to form new master reticles, and reduced images of the newly formed master reticles are exposed while stitching screens using an optical-type projection exposure apparatus.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a producing method of a mask inwhich an original or master plate to be transferred onto a substratesuch as a wafer in a lithography process for producing semiconductordevices, image pickup devices (CCDs etc.), liquid crystal displays,plasma displays, thin film magnetic heads and the like. The presentinvention also relates to an exposure method and an exposure apparatusused for this producing method. For example, the invention is suitablyused for producing a mask and the like such as a transparent reticleusing excimer laser as exposure beam, a reflective reticle using EUVlight such as soft X-ray as the exposure light, and a membrane structureusing electron beam as the exposure beam.

[0003] 2. Description of the Related Art

[0004] Conventionally, when a semiconductor device is produced, in orderto transfer a pattern of a reticle (or photo-mask) as a mask onto eachshot region of a wafer on which a photoresist is applied, an i line(wavelength 365 nm) of a mercury lamp as exposure beam, or KrF excimerlaser (wavelength 248 nm) is used, and a projection exposure apparatus(stepper or the like) using a projection optical system having thenumber of openings NA of about 0.7 is used. If a wavelength of theexposure beam is defined as λ and a predetermined process coefficient isdefined as k, resolution on a wafer is expressed as k×λ/NA. Therefore, aconventional minimum line width of an image of a line and space patternthat can be transferred onto the wafer is about 180 nm. The size of theconventional reticle is usually 5×5 inches or 6×6.

[0005] In this case, since a projection magnification of a projectionoptical system is about ¼ or ⅕, a line width of a pattern of a reticlecorresponding to the minimum line width (when the projectionmagnification is ¼) is about 720 nm. A conventional reticle having sucha pattern is produced by directly forming the original pattern on apredetermined substrate using an electron beam drawing apparatus.

[0006] As described above, the conventional reticle is produced bydirectly forming, onto a substrate of about 6×6 inches at the maximum,an original pattern whose a minimum line width becomes about 180 nm on awafer. However, since the electron beam drawing apparatus continuouslyforms various portions of the original pattern with beams of apredetermined cross sectional shape, there is inconvenience that thepattern-forming time becomes long and the producing time of reticlebecomes long. Especially, since the same reticles are usually used asworking reticles concurrently by a plurality of producing lines, it isnecessary to produce a plurality of reticles having the same originalpattern. At that time, the pattern of each of the working reticles isformed by the electron beam drawing apparatus, time required forproducing the reticles becomes extremely long.

[0007] Further, precision of about 5% of the minimum line width in anentire surface of the reticle is required as pattern-forming precision.Therefore, if the minimum line width is 720 nm, precision of about 36 nmis required. Thus, when the size of the reticle is 6×6 inches, precisionof about 36 nm (≈2.4×10⁻⁷) is required for length of about 150 mm. Suchprecision is almost limit of the current electron beam drawing apparatuswhen drift of electron beam is taken into consideration.

[0008] Further, the resolution will further be improved so as to meetthe increased packing density of the semiconductor device and the like.That is, for future several years, in order to transfer a pattern havingthe minimum line width of about 180 to 100 nm onto a wafer, ArF excimerlaser light (wavelength is 193 nm), F₂ laser light (wavelength is 157nm) and laser light of vacuum ultraviolet (VUV) such as solid laser andthe like are under review. As a reticle for exposure beam of the vacuumultraviolet longer than about 100 nm, a transparent reticle usingfluorite (CaF₂) as a substrate can be used.

[0009] In order to further enhance the resolution for the nextgeneration semiconductor device, an exposure apparatus in which extremeultraviolet light (EUV light) such as soft X-ray (wavelength is about 13to 6 nm) is used as exposure beam, and reflection system of reducedmagnification using a combination of about three to five concave mirrorsand convex mirrors is used as the projection optical system is underdevelopment. When the EUV light is used, since there is not opticalmaterial having excellent transmittance, it is considered that a reticleto be used is a transparent reticle.

[0010] The use of an electron beam exposure apparatus in which a mask(stencil mask or the like) of a membrane structure having predeterminedopening patterns in thin film members formed on a wafer into a latticeshape is irradiated with electron beam, an image of the opening patternin the film member is transferred onto a substrate to be exposed whilestitching screens at reduced magnification, thereby transferring apattern of large area at high resolution is also under review. It isexpected that resolution of about 130 to 30 nm can be obtained using theexposure apparatus or the electron beam exposure apparatus using the EUVlight.

[0011] In order to obtain resolution of about 180 to 30 nm on a wafer,if the projection magnification of the projection optical system is ¼,the minimum line width of the reticle pattern is about 720 to 120 nm. Itis expected that the size of the future reticle will be about 9×9inches. Therefore, if the pattern-forming precision is about 5% of theminimum line width, precision required for the electron beam drawingapparatus is about 36 to 6 nm (about 1.6×10⁻⁷ to 2.6×10⁻⁸) with respectto a length of about 230 nm, but it is difficult under presentcircumstances to realize such a high precision. Further, if the area ofthe reticle becomes greater and the pattern becomes finer, thepattern-forming time becomes longer. Therefore, especially when aplurality of working reticles are produced, there is inconvenience thatthe producing time becomes excessively long.

[0012] In recent years, attention is directed toward technique fordisposing previously designed various circuit units such as CPU ormemory into a predetermined arrangement, these units are connected toone another through wires, thereby producing a semiconductor device thatcan achieve a desired function as in a case in which ASIC(application-specific IC) is produced. According to this technique, itis possible to develop semiconductor devices having various functions ina short time and thus, it is expected that the technique will widely beutilized in fields of multimedia, digital TV and the like. However, insuch a case also, if the original pattern of each reticle is formedusing the electron beam drawing apparatus, since the producing time ofthe reticle becomes long, there is inconvenience that developing timecan not be shortened so much especially when various semiconductordevices are developed.

[0013] Thereupon, recently, a method in which an original pattern havingan enlarged pattern on a reticle is prepared, this original pattern isdivided into a plurality of parent patterns, they are formed on masterreticles, images of the patterns of the plurality of master reticles aretransferred onto a glass substrate while stitching screens usingreduction projection type exposure apparatus, thereby producing reticles(working reticles) for actually light exposure is under review. When theimage is transferred while stitching screens in this manner, it isnecessary to reduce stitching error of a boundary portion (stitchingportion) of adjacent parent patterns, and to reduce variation inexposure light amount in the vicinity of the boundary portion.

[0014] As an exposure method that can be used to reduce the stitchingerror and to reduce variation in exposure light amount, there is amethod as disclosed in Japanese Patent Application Laid-open No.6-132195 and corresponding U.S. Pat. No. 5,477,304 in which in order totransfer an image of a reticle pattern in each shot region on a waferwhile stitching the screens, illumination distribution of illuminationregion of the exposure light is formed into a trapezoidal shape in whichopposite ends are gradually lowered, and image of adjacent reticlepatterns are overlapped on a boundary portion of a predetermined width.As a first method for forming the illumination distribution of theillumination region into the trapezoidal shape, there is a method inwhich a disposing surface of a reticle blind (variable field aperture)for defining the illumination region is defocus on the illuminationregion (pattern surface of reticle). According to this method, however,when shape of the opening aperture of an illumination optical system isswitched from a circle (normal illumination) to a plurality ofdecentered opening (deformed illumination), there is an adversepossibility that the shape of the illumination distribution is nottrapezoidal shape.

[0015] In order to prevent the shape of the illumination distributionfrom being deformed, the defocus amount of the reticle blind may bevaried in accordance with illumination condition for example, but thereis inconvenience that the mechanism of the illumination optical systemis complicated.

[0016] Further, in order to form the illumination distribution of theillumination region into substantially the trapezoidal shape, there isproposed a method for moving a blade constituting the reticle blind intoexposure light. However, there is inconvenience that this method alsocomplicates a driving mechanism of the reticle blind and the mechanismof the illumination optical system is complicated.

[0017] There is considered a method for forming the illuminationdistribution of the illumination region into the trapezoidal shape bymaking ends of the reticle blind disposed in conjugate position with theillumination region semi-transparent. According to this method, however,if a foreign substance is attached to the semi-transparent portion,uneven illumination is generated in the illumination region. In order toavoid this, it is necessary to enhance the precision of a dustproofmechanism for gas supplied to the illumination optical system.Therefore, there is inconvenience that the mechanism of the illuminationoptical system is complicated.

SUMMARY OF THE INVENTION

[0018] In view of the above circumstances, it is a first object of thepresent invention to provide a producing method of a mask capable ofproducing a mask on which a transfer pattern is formed in a short timewith high precision.

[0019] It is a second object of the invention to provide a producingmethod capable of producing, in a short time, a mask having a patternwhich can be formed by disposing various circuit units according to apredetermined positional relation and by connecting the units throughwire patterns or the like.

[0020] It is a third object of the invention to provide a producingmethod of a mask on which a fine transfer pattern of a large area isformed in a short time with high precision.

[0021] It is a fourth object of the invention to provide a projectionexposure method in which when a transfer pattern is divided into aplurality of patterns and images of the patterns are transferred whilestitching screens, a mechanism of an illumination optical system is notcomplicated, stitching error of boundary portions of images between aplurality of patterns is reduced, and uneven exposure light amount inthe vicinity of the boundary portion can be reduced.

[0022] It is a fifth object of the invention to provide a projectionexposure method when one mask pattern is produced while stitchingscreens, stitching error of images of a plurality of patterns and themask pattern can be produced with high precision.

[0023] It is another object to provide a projection exposure apparatuscapable of carrying out the above projection exposure method, and aproducing method of a device using the projection exposure method.

[0024] According to a first aspect of the present invention, there isprovided a producing method of a mask formed with a transfer pattern andto be irradiated with a predetermined exposure beam, comprising:

[0025] making design data of an original pattern obtained by enlargingthe transfer pattern, applying photosensitive material into which acoloring matter which absorbs light in a predetermined wavelength regionis mixed onto at least one first substrate, and forming at least aportion of the original pattern on the first substrate,

[0026] developing the photosensitive material on the at least one firstsubstrate, and

[0027] with the at least one first substrate being used as a parent maskhaving a mask pattern made of the photosensitive material remained afterdeveloping the photosensitive material, exposing a reduced image of thepattern of the parent mask onto a second substrate while stitching thereduced image using a projection exposure apparatus which carries outreduction projection using illumination light in a wavelength regionabsorbed by the photosensitive material.

[0028] According to the mask producing method of the first aspect of thepresent invention, the original pattern obtained by enlarging thetransfer pattern is formed on the first substrate by an electron beamdrawing apparatus for example. Then, using photosensitive material leftby development of the photosensitive material on the first substrate isused as the mask pattern, and the mask pattern is reduction projectedusing the exposure apparatus using light having wavelength regionabsorbed by coloring matter in the photosensitive material as exposurelight. With this method, the mask can be produced at high speed withoutcarrying out a step such as deposition of chromium film and etching withrespect to the first substrate. This electron beam drawing apparatus mayform the enlarged pattern of the transfer pattern. Thus, if theenlargement magnification is set to α, an influence of thepattern-forming error is reduced to about 1/α and thus, the transferpattern is formed with high precision.

[0029] According to a second aspect of the present invention, there isprovided a producing method of a mask formed with a transfer pattern,comprising

[0030] dividing the transfer pattern into an existing pattern portionand a newly-forming pattern portion based on design data of the transferpattern,

[0031] forming an original pattern corresponding to a pattern of thenewly-forming pattern portion onto a first substrate to prepare a firstparent mask, and

[0032] with a mask formed with another original pattern corresponding toa pattern of the existing pattern portion being used as a second parentmask, exposing images of patterns of the first and second parent masksonto a second substrate which is to become the mask while stitching theimages.

[0033] According to the mask producing method of the second aspect ofthe present invention, only the original pattern corresponding to thenewly-forming pattern is newly formed by the electron beam drawingapparatus for example, and an already-formed parent mask is commonlyused for the second parent mask on which the original patterncorresponding to the existing pattern is formed. In this case, since thenewly-forming pattern is a portion of the entire transfer pattern, ifthe ratio of the patern-forming error with respect to the entire lengthof the pattern to be formed is judged as being substantially constant,the pattern-forming error of the newly-forming pattern can be reduced ascompared with a case in which the entire original pattern is formed.Therefore, as compared with a case in which the entire original patternis formed by the electron beam drawing apparatus, it is possible to formthe mask in a short time and with high precision.

[0034] According to a third aspect of the present invention, there isprovided a producing method of a mask formed with a transfer patternincluding a predetermined linear pattern, comprising:

[0035] diving an enlarged pattern of the transfer pattern into aplurality of parent patterns from a position corresponding to anintermediate portion of the linear pattern as a boundary portion, and

[0036] projecting and exposing reduced images of the plurality of parentpatterns onto a substrate which is to become the mask while stitchingthe reduced images, wherein,

[0037] portions of the plurality of parent patterns corresponding to theboundary portion of the linear pattern are provided with overlappedportions each having a predetermined width in its longitudinaldirection, and the overlapped portions are respectively provided withtapered portions each having a wide tip end.

[0038] According to the mask producing method of the third aspect of thepresent invention, the enlarged pattern is divided into a plurality ofparent patterns, and the images of the parent patterns are transferredwhile stitching the screens. With this method, the transfer patternhaving large area can be formed in a short time. If a design length ofthe overlapping portion of the reduced images of the plurality of parentpatterns is defined as 2×ΔL, and if the reduced images are stitched andexposed, a boundary portion having a length of 2×ΔL and a thick centralportion is formed in a state in which there is no positional deviationunder normal exposure light amount. However, the overlapping portion isexposed twice and is also exposed to light that wraps around. Thisboundary portion can be made substantially flatly by increasing theexposure light amount (over exposure). At that time, even if thepositioning error of about ±ΔL of the reduced images of the parentpatterns is generated in the longitudinal direction and in a directionintersecting with the longitudinal direction, the boundary portion doesnot become thin. Therefore, a fine pattern can be formed with highprecision.

[0039] According to a fourth aspect of the present invention, there isprovided a projection exposure method, comprising:

[0040] diving a predetermined pattern into a plurality of mask patterns,and exposing images of the plurality of mask patterns onto a substratewhile stitching screens through a projection optical system, therebytransferring an entire image of the predetermined pattern onto thesubstrate, wherein

[0041] when the predetermined pattern is divided into the plurality ofmask patterns, boundary portions of adjacent two mask patterns arerespectively provided with overlapping portions of superposed portions,

[0042] when an image of each mask pattern of the plurality mask patternsis exposed onto the substrate through the projection optical system,

[0043] the mask pattern and the substrate are moved in synchronouslywith a predetermined visual field of the projection optical system suchthat the pattern of the mask pattern other than the overlapping portiondoes not come out from the predetermined visual field and a pattern ofthe overlapping potion goes out from the visual field.

[0044] According to the projection exposure method of the fourth aspectof the present invention, by exposing the image while stitching thescreens using a static exposure type (full field exposure type)projection exposure apparatus, the image of one pattern is transferredonto the substrate. That is, as shown in FIG. 17A1, a substrate 218 ispositioned such that most part of partial overlapping portions 237A and240A in a mask pattern with respect to a visual field is within a visualfield 210, and remaining overlapping portions 238A and 239A are out ofthe visual field 210. After the substrate 218 is positioned such thatoverlapping error is within a tolerance, the visual field 210 isirradiated with exposure beam with uniform illumination distribution.

[0045] Thereafter, the mask pattern is moved in a direction shown withan arrow 243R with respect to the visual field 210, and when theremaining overlapping portions 238A and 239A come within the visualfield 210 completely as shown in FIGS. 17B1 and 17C1, the irradiation ofthe exposure beam is stopped. With this operation, the distribution ofthe exposing amount on the corresponding substrate 218 is formed into atrapezoidal shape as shown with a folded line 244A in FIG. 18A forexample. That is, a trapezoidal illumination distribution can beobtained without complicating the mechanism of the illumination opticalsystem, and uneven exposure light amount in the vicinity of the boundaryportion obtained by overlapping the adjacent mask pattern images isreduced.

[0046] Further, as shown in FIGS. 17A2, 17B2 and 17C2, if the substrate218 is moved with respect to an exposure region 230 that is conjugatewith the visual field 210 in synchronism with movement of each maskpattern, the stitching error in the boundary portion of the adjacentmask pattern images is reduced by effect of average.

[0047] According to a fifth aspect of the present invention, there isprovided a projection exposure method, comprising:

[0048] diving a predetermined pattern into a plurality of mask patterns,and exposing images of the plurality of mask patterns onto a substratewhile stitching screens through a projection optical system, therebytransferring an entire image of the predetermined pattern onto thesubstrate, wherein

[0049] the predetermined pattern is divided into the plurality of maskpatterns along at least a predetermined direction, boundary portions ofadjacent two mask patterns in the predetermined direction are providedwith overlapping portions of superposed portions,

[0050] when an image of each mask pattern of the plurality of maskpatterns is exposed onto the substrate through the projection opticalsystem,

[0051] in a state in which an image of a pattern, of the mask pattern,in a visual field which is fixed to the projection optical system and iselongated in the predetermined direction is exposed onto the substratethrough the projection optical system, the mask pattern and thesubstrate are scanned in synchronously with each other at the same speedratio as a projection magnification of the projection optical system ina direction intersecting substantially at right angles with thepredetermined direction with respect to the visual field, and

[0052] the mask pattern and the substrate are moved in synchronouslywith each other in the predetermined direction in accordance withexposure time and a width of the overlapping portion of the mask patternwith respect to the visual field.

[0053] According to the projection exposure method of the fifth aspectof the present invention, one pattern image is transferred onto thesubstrate 259 by exposing the image using a scanning type projectionexposure apparatus such as a step and scan type while stitching screens.At that time, as shown in FIG. 19 for example, widths (in apredetermined direction) of opposite side overlapping portions 253, 254of a mask pattern 255 to be exposed and a portion 252 except theseportions 253, 254 are defined as L1 and L1, and a width of the visualfield 210 on the mask pattern in the predetermined direction is definedas L2, the width L2 is set as follows:

L2=11+2×L  (1)

[0054] In order to make the illumination distribution with respect tothe overlapping portion such that the illumination distribution as awhole becomes smaller as approaching the end thereof, if a width in ascanning direction intersecting with the predetermined direction(direction to be scanned) of the visual field is defined as H andscanning speed of the mask pattern with respect to the visual field isdefined as VR, it is desirable that the mask pattern is vibrated (moved)with amplitude L with respect to the direction to be scanned and withcycle TR satisfying the following conditions using one or more integersn as one example:

VR×TR=H/n  (2)

[0055] i.e.,

TR=H/(n×VR)  (3)

[0056] This means that when the mask pattern is moved through the widthH of the visual field in the scanning direction, the mask pattern isvibrated n-times in the direction to be scanned as shown in FIGS. 19A to19E. With this, the mask pattern is moved along a sinusoidal wave withrespect to the visual field, the distribution of the exposure lightamount on the substrate after the scanning exposure is formed into thetrapezoidal shape as shown with a curved line 258A in FIG. 20 forexample, and the uneven exposure light amount in the vicinity of theboundary portion obtained by overlapping the images of the adjacent maskpatterns becomes small.

[0057] Further, if the substrate 259 is moved along a sinusoidal wavewith respect to an exposure region 230S that is conjugate with thevisual field 210S in synchronism with movement of each mask patternalong a sinusoidal wave as shown in FIG. 19F for example, the stitchingerror in the boundary portion of the adjacent mask pattern images isreduced by effect of average.

[0058] Furthermore, in the projection exposure methods of the fourthaspect and fifth aspect of the present invention, if a predeterminedpattern to be transferred onto the substrate is one mask pattern,stitching error when the mask pattern is exposed to light by screenstitching method is reduced.

[0059] According to a sixth aspect of the present invention, there isprovided a projection exposure apparatus which exposes a pattern formedon a mask onto a substrate through a projection optical system, theprojection optical system being an optical system which exposes an imageof a pattern of the mask within a predetermined visual field onto thesubstrate, comprising:

[0060] a mask stage capable of holding the mask and moving in apredetermined direction,

[0061] a substrate stage capable of holding the substrate and movingtwo-dimensionally including the predetermined direction, and

[0062] a control system which drives the mask stage and the substratestage to move the mask and the substrate in synchronous with each otherin the predetermined direction such that, when an entire image of thepattern of the mask is exposed onto the substrate through the projectionoptical system, a portion of the pattern of the mask does not come outfrom the visual field and a pattern other than the portion goes out fromthe visual field.

[0063] According to the projection exposure apparatus of the sixthaspect of the present invention, the projection exposure method of thefourth aspect of the present invention can be carried out.

[0064] According to a seventh aspect of the present invention, there isprovided a projection exposure apparatus which exposes a pattern formedon a mask onto a substrate through a projection optical system, theprojection optical system being an optical system which exposes an imageof the pattern of the mask in a visual field which is longer in apredetermined direction, comprising:

[0065] a mask stage capable of holding the mask and moving in thepredetermined direction and in a direction intersecting substantially atright angles with the predetermined direction,

[0066] a substrate stage capable of holding the substrate and moving ina two-dimensional directions including the predetermined direction, and

[0067] a control system which, when an image of a pattern of the mask inthe visual field is exposed onto the substrate through the projectionoptical system, drives the mask stage and the substrate stage to movethe mask stage and the substrate stage in synchronous with each other ina direction intersecting the predetermined direction substantially atright angles and to move the mask and the substrate in the predetermineddirection in synchronous with each other such that an end of the patternof the mask goes out from the visual field by a predetermined width.

[0068] According to the projection exposure apparatus of the seventhaspect of the present invention, the projection exposure method of thefifth aspect of the present invention can be carried out.

[0069] According to a eighth aspect of the present invention, there isprovided a producing method of a device comprising a step fortransferring a device pattern (including a mask pattern, a pattern for asemiconductor device, etc.) onto a work piece using a projectionexposure method as recited in claim 4.

[0070] According to a ninth aspect of the present invention, there isprovided a projection exposure method, comprising the step oftransferring a mask pattern is transferred to a plurality block regionsarranged in a first direction on a substrate through a projectionoptical system to form a predetermined pattern on the substrate,peripheral portions of the block regions being partially overlapped,wherein

[0071] in order to transfer the mask pattern to one block region of theplurality of block regions, the mask pattern and the substrate are movedin synchronous with each other with respect to a predetermined regionwhere energy beam is irradiated within a visual field of the projectionoptical system, and moving directions of the mask pattern and thesubstrate are set to a direction which is intersecting with the firstdirection and with a second direction which intersects with the firstdirection at right angles such that an irradiating amount of the energybeam is gradually reduced at the peripheral portion in the one blockregion with respect to the first direction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The above and further objects, features and advantages of thepresent invention will become more apparent from the following detaileddescription taken in conjunction with the accompanying drawings,wherein;

[0073]FIG. 1 is a block diagram showing a reticle designing system and areticle producing system used in a first embodiment of the presentinvention;

[0074]FIG. 2 is a block diagram showing a projection exposure apparatuscomprising an excimer laser light source 2 and an light exposing section32 in FIG. 1;

[0075]FIG. 3A is a plan view showing a working reticle 43 to beproduced;

[0076]FIG. 3B is a plan view showing a reflective reticle 45 to beproduced;

[0077]FIG. 4 is a diagram showing a master reticle corresponding topartial existing pattern portion shown in FIG. 3A;

[0078]FIG. 5 is a diagram showing a master reticle corresponding topartial newly-forming pattern portion shown in FIG. 3A;

[0079]FIG. 6 is a side view showing the master reticle for the existingpattern;

[0080]FIGS. 7A to 7C are diagrams showing a producing procedure of themaster reticle for the newly-forming pattern portion;

[0081]FIGS. 8A to 8C are flowcharts showing one example of operationfrom a designing procedure of the reticle to a producing procedure inthe embodiment of the invention;

[0082]FIGS. 9A to 9C are explanatory diagrams when exposure is carriedout while stitching screens in the embodiment;

[0083]FIGS. 10A to 10C are diagrams showing shape of linear patternobtained when over exposure is carried out while exposure light amountis increased gradually in the example shown in FIGS. 9A to 9C;

[0084]FIGS. 11A to 11C are diagrams showing influence of lateraldeviation at the time of stitching exposure in the example shown inFIGS. 9A to 9C;

[0085]FIGS. 12A to 12C are diagrams showing variation in shape of thelinear pattern obtained when the lateral deviation is generted;

[0086]FIGS. 13A to 13C are diagrams showing variation in shape whenpositional deviation of the linear pattern is generated in itslongitudinal direction;

[0087]FIG. 14 is a block diagram showing a projection exposure apparatusused in a second embodiment of the invention;

[0088]FIG. 15 is a diagram showing a pattern arrangement of a workingreticle WR, and pattern arrangement of corresponding master reticle RAand RB produced in the second embodiment of the invention;

[0089]FIG. 16 is a perspective view of an essential portion used forexplanation when an image of a pattern of the master reticle RA isprojected onto a glass substrate 218 using the projection exposureapparatus shown in FIG. 14;

[0090] FIGS. 17A1, 17A2, 17B1, 17B2, 17C1 and 17C2 are explanatorydiagrams when exposure is carried out while moving the master reticle RAand the glass substrate 218 in synchronism with each other in the secondembodiment;

[0091]FIGS. 18A and 18B are diagrams showing one example of distributionof an integrating exposure light amount obtained by exposure action ofFIGS. 17A1, 17A2, 17B1, 17B2, 17C1 and 17C2;

[0092]FIGS. 19A to 19F are explanatory diagrams when exposure is carriedout while moving a master reticle 251A and a glass substrate 259 insynchronism with each other in a third embodiment of the invention;

[0093]FIG. 20 is a diagram showing one example of distribution of anintegrating exposure light amount obtained by exposure action of FIGS.19A to 19F; and

[0094] FIGS. 21A1, 21A2, 21B1, 21B2, 21C1 and 21C2 show exposure actionin the third embodiment of the invention, and modifications thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0095] A preferred first embodiment of the present invention will beexplained below with reference to the drawings.

[0096]FIG. 1 shows a designing system of a reticle as a mask, and areticle producing system 41 for producing a working reticle on which atransfer pattern is formed that is designed by the reticle designingsystem. In FIG. 1, a reticle pattern corresponding to a circuit patternof each layer of a semiconductor device is partially designed in each ofdesign terminals 39 a to 39 d comprising compact computers. Allotmentand the like of design regions in the terminals 39 a to 39 d are managedthrough a network by a circuit design centralized control apparatus 38comprising a medium computer.

[0097] A reticle pattern designed in this manner has a portion requiringstrict line width precision and a portion requiring relatively soft linewidth precision. In each of the terminals 39 a to 39 d, identificationinformation for identifying a position of a circuit that can be divided(portion requiring soft line width precision) is generated, and thisidentification information is transmitted to the circuit designcentralized control apparatus 38 together with design data of thepartial reticle pattern. The circuit design centralized controlapparatus 38 transmits design data information of the reticle patternused in each layer, and the identification information indicating theposition that can be divided, to a procedure managing apparatus 40comprising a medium computer in the reticle producing system 41 throughthe network.

[0098] The reticle producing system 41 of the present embodiment dividesan original pattern obtained by enlarging the reticle pattern with apredetermined magnification α (α is four times or five times) into aplurality of original patterns at dividing positions determined by theidentification information, and forms these divided original patterns onthe master reticles as parent masks. Alternatively, existing masterreticle is used for a portion of the divided original pattern. Imagesobtained by reducing patterns of the plurality of master reticles insize into 1/α are exposed (stitched and exposed) to light on apredetermined substrate while stitching screens, thereby producing theworking reticle used when a circuit pattern of each layer of asemiconductor device or the like is produced.

[0099] Main members constituting the reticle producing system 41 are, inaddition to the procedure managing apparatus 40, an EB (electron beam)pattern-forming section 33, an excimer laser light source 2 as anexposure light source, an light exposing section 32, and a cotardevelopers section 37. The EB pattern-forming section 33 comprisesquartz, fluorite (CaF₂) or the like, and comprises an electron beamdrawing apparatus for forming a predetermined new pattern on a substrateon which electron beam resist is applied using exposure beam. Areduction projection type projection exposure apparatus is constituted.The projection exposure apparatus carries out the stitching exposure ofan image of a master reticle using excimer laser light as exposurelight. The projection exposure apparatus of the present embodiment islargely different from a conventional photo repeater in that reducedimage of various master reticles having different sizes are exposed tolight while stitching screens.

[0100] In addition to the above members, disposed in the reticleproducing system 41 are, cotar developer sections 37 existing in vacuumatmosphere in the EB pattern-forming section 33 and a predeterminedatmospheric pressure atmosphere, substrate transfer section 34 forreceiving and sending a substrate between the substrate transfer section34 and the light exposing section 32, a substrate accommodating section36 for accommodating a plurality of substrate for master reticles andworking reticles, and an existing reticle accommodating section 35 foraccommodating a plurality of master reticles on which existing patternsare previously formed on predetermined substrates by chromiumdeposition.

[0101] Next, a structure of the projection exposure apparatus comprisingthe excimer laser light source 2 and the light exposing section 32 willbe explained with reference to FIG. 2. The projection exposure apparatusof the present embodiment is a step and scan type exposure apparatususing a catadioptric system as the projection optical system.

[0102]FIG. 2 shows the projection exposure apparatus of the presentembodiment. In FIG. 2, as the excimer laser light source 2, an ArFexcimer laser light source having a half-width of oscillation spectrumof about 1 pm or less when oscillation wavelength is 193 nm is used. AKrF excimer laser light source may be used instead. The invention can beapplied even when an F₂ laser light (wavelength is 157 nm), a solidlaser light source or a mercury lamp is used as the exposure lightsource. Illumination light IL comprising pulse light irradiated from theexcimer laser light source 2 whose light-emitting state is controlled byan exposure control apparatus 1 is deflected by a mirror 3 and reaches afirst illumination system 4.

[0103] The first illumination system 4 includes a beam expander, a lightamount variation mechanism, a fly eye lens as an optical integrator(homogenizer) and the like. An ejection surface of the firstillumination system 4 (ejection side focus surface of the fly eye lensin the present embodiment) is formed with a two-dimensional light sourcein which a large number of light source images are distributed in asurface-shape. A changing revolver 5 (corresponding to an aperturevariable plate 205 of an example in FIG. 14) for variously changingillumination conditions is disposed on a formation surface of thetwo-dimensional light source. The changing revolver 5 is formed at itsside surface with a normal circle opening aperture, so-calleddeformation illumination opening apertures comprising a plurality ofopenings deviated from the optical axis, a band-like opening aperture, asmall α value-opening aperture and the like. A predeterminedillumination system opening aperture (α aperture) is disposed on theejecting surface of the first illumination system 4 by rotating thechanging revolver 5 through a changing apparatus 6. For example, theillumination condition is optimized in accordance with a fine degree ofa pattern of a master reticle as a parent mask which will be describedlater.

[0104] The operation of the changing apparatus 6 is controlled by theexposure control apparatus 1, and the operation of the exposure controlapparatus 1 is controlled by a main control apparatus 7 thatcollectively controls the operation of the entire apparatus. In thepresent embodiment, in order to carry out the slicing exposure ofreduced images of a plurality of master reticles 46A, 55A, . . . ,exposure data of the master reticles are supplied by the proceduremanaging apparatus 40 shown in FIG. 1. In FIG. 2, light exposure of themaster reticle 46 as a representative will be explained. Theillumination light IL passing through the illumination system openingaperture set by the changing revolver 5 enters a beam splitter 8 havinggreat transmittancy. A very small amount of illumination light reflectedby the beam splitter 8 is received by an integrator sensor 9 comprisinga photodetector, and a detection signal of the integrator sensor 9 issupplied to the exposure control apparatus 1. The detection signal isused for indirectly monitoring the exposure light amount on the wafer.

[0105] Illumination light IL that passed through the beam splitter 8illuminates an illumination visual field aperture system (reticle blindsystem) 11 through a second illumination system 10. The illuminationvisual field aperture system 11 is divided into a movable blind and astationary blind. The stationary blind is a visual field aperture havinga fixed thin and long rectangular opening. The movable blind includestwo pairs of movable blades which can move independently in a scanningdirection and in a direction to be scanned (to-be scanned direction,hereinafter) and which can open and close. A disposition surface of thestationary blind is separated from a conjugate surface of the patternsurface of the master reticle 46A through a predetermined distance inthe optical axis direction. By opening the stationary blind, theillumination region with respect to the master reticle 46A is set to thethin and long rectangular shape. When the scanning exposure by themovable blind disposed on the conjugate surface of the master reticle46A is started and completed, an opening of the stationary blind isgradually opened and closed respectively. With this operation, a regionof the working reticle 43 other than its original exposure region as asubstrate to be exposed is prevented from being irradiated withillumination light.

[0106] In the present embodiment, as will be described later, in themaster reticle 55A, only a portion of pattern selected from the patternregion is exposed to light. Therefore, when only the portion of patternis selected in this manner, the movable blind in the illumination visualfield aperture system 11 is used. The operation of the movable blind inthe illumination visual field aperture system 11 is controlled by adriving apparatus 12. When the master reticle 46A and the like and theworking reticle 43 are scanned in synchronously with each other by astage control apparatus 13, the stage control apparatus 13 drives themovable blind in synchronously through the driving apparatus 12. Theillumination IL that passed through the illumination visual fieldaperture system 11 passes through a third illumination system 14 andilluminate the rectangular illumination region 15 of the pattern surface(lower surface) of the master reticle 46A with a uniform illuminationdistribution.

[0107] In the following explanation, the X axis is intersecting with apaper sheet of FIG. 2 in a plane that is in parallel to a patternsurface of the master reticle 46A that is being exposed to light, the Yaxis is in parallel to the paper sheet of FIG. 2, and the Z axis isintersecting with the pattern surface. At that time, the scanningdirection of reticle at the time of scanning and exposure is set intothe Y direction. A pattern in the illumination region 15 on the masterreticle 46A is reduced in size into projection magnification β (β is ¼,⅕ or the like for example) through a projection optical system PL thatis telecentric on both sides (or one side closer to an image side) heldin a column 25, and projected onto an exposure region 16 on the workingreticle 43 to which photoresist is applied. The projection magnificationβ is set to a reciprocal of the enlargement magnification α of thepattern of the working reticle (β=1/α).

[0108] The projection optical system PL is a catadioptric system havingthe number of openings NA of about 0.7, and a distortion correctingplate 42 for correctly correcting distortion is disposed on an upper endof an object surface side. In order to carry out the stitching exposure,for example, screens of reduced images which are adjacent to one anotherin lateral and vertical directions of the exposure region 16 of theprojection optical system PL are stitched in some cases. In this case,if a distortion state is different depending upon a position in theexposure region 16, there is an adverse possibility that stitching errorexceeding tolerance is generated. Thereupon, the distortion state in theexposure region 16 of the projection optical system PL is previouslymeasured, and the distortion correcting plate 42 is formed withprojections and depressions such that distortions in various positionsin the exposure region 16 are within the tolerance based on the measuredresult. The splicing error due to the distortion can be reduced to anextremely low level by the distortion correcting effect and effect ofaveraging by means of scanning and exposure.

[0109] In FIG. 2, the master reticle 46A is held on a reticle stage 17.The reticle stage 17 can move at constant speed in the Y direction by alinear motor in a state in which the reticle stage 17 is placed on areticle support base 18 through an air bearing. The reticle stage 17 canalso move slightly in the X direction, the Y direction and the rotationdirection (θ direction). A position of the reticle stage 17 (masterreticle 46A) in the X direction and Y direction is always measured withresolution of about 0.001 μm (1 nm), and rotation angle of the reticlestage 17 is also measured. Based on the measured value, the stagecontrol apparatus 13 controls the operation of the reticle stage 17.

[0110] In the present embodiment, since it is necessary to replace theplurality of master reticles 45A, 55A, . . . , a reticle library foraccommodating enough reticles which are necessary for exposure, and areticle replacing mechanism (not shown) are disposed in the vicinity ofthe reticle support base 18. The main control apparatus 7 replaces themaster reticle on the reticle stage 17 at high speed through the reticlereplacing mechanism in accordance with exposure sequence.

[0111] On the other hand, a substrate of the working reticle 43 to beproduced is held on a sample stage 21 through a substrate holder 20, thesample stage 21 is placed on a substrate stage 22, and the substratestage 22 is placed on a surface plate 23 through an air bearing. In thisstate, the substrate of the working reticle 43 can move at a constantspeed in the Y direction by the linear motor, and can stepwisely move inthe X direction and the Y direction. A Z stage mechanism for moving thesample stage 21 in the Z direction, and a tilt mechanism (levelingmechanism) for adjusting an inclination angle of the sample stage 21 areincorporated in the substrate stage 22.

[0112] A position of the sample stage 21 (working reticle 43) in the Xdirection and Y direction is always measured with resolution of about0.001 μm (1 nm) by a moving mirror 24m fixed to a side surface of thesample stage 21 and a laser interferometer 24 fixed to a column (notshown), and rotation angle and tilt angle of the sample stage 21 arealso measured. Based on the measured values, the stage control apparatus13 controls the operation of the substrate stage 22. The substrate stage22 of the present embodiment corresponds to a wafer stage of a normalexposure apparatus. The projection exposure apparatus of the presentembodiment can also be used as an exposure apparatus for producingsemiconductor devices by replacing the substrate holder 20 with a holderfor semiconductor device wafer.

[0113] At the time of scanning and exposure, a command to start theexposure is sent from the main control apparatus 7 to the stage controlapparatus 13, and in reply thereto, the stage control apparatus 13 scansthe working reticle 43 in the Y direction at a speed of β×VR (β isprojection magnification) through the substrate stage 22 insynchronously with the scanning of the master reticle 46A in the Ydirection at a speed VR. An oblique-incidence type multipoint autofocussensor (“AF sensor”, hereinafter) 26 for measuring positions of asurface of the working reticle 43 at a plurality of measuring points inthe Z direction (focus position) is disposed on a side surface of theprojection optical system PL. Based on the measured value of themultipoint AF sensor 26, a focus/tilt control apparatus 27 obtains afocus position and an inclination angle of the surface of the workingreticle 43. This measured value is supplied to the stage controlapparatus 13 through the main control apparatus 7. Based on the suppliedmeasured value, the stage control apparatus 13 controls a Z stagemechanism and the like in the sample stage 21 by an autofocus manner andan auto-leveling manner, and stitches the surface of the working reticle43 with an image of the projection optical system PL.

[0114] An off-axis type alignment sensor 28 is fixed to a side surfaceof the projection optical system PL. At the time of alignment, aposition of a mark (alignment mark) formed on an outer side of a patternregion for example of the working reticle 43 is detected by thealignment sensor 28 and an alignment signal processing apparatus 29connected to the alignment sensor 28. A measured value of the laserinterferometer 24 is also supplied to the alignment signal processingapparatus 29. The positions of the mark are coordinates on the stagecoordinate system (X, Y) determined based on the X coordinate and Ycoordinate measured by the laser interferometer 24. The positions of themark are supplied to the main control apparatus 7. A pair of reticlealignment microscopes (although they are not illustrated, theycorresponds to reticle alignment microscopes 232A and 232B in FIG. 16)for detecting positions of two alignment marks of the reticle aredisposed on upper portions of the master reticle 46A. A reference markmember FM (corresponding to a reference mark member 224 in FIG. 16) onwhich a reference mark for alignment is formed is fixed in the vicinityof the substrate holder 20 on the sample stage 21.

[0115] At the time of alignment of the master reticle 46A, a positionaldeviation amount between the alignment mark on the master reticle 46Aand a predetermined reference mark on the reference mark member FM isdetected by the pair of reticle alignment microscopes. By adjusting theposition of the reticle stage 17 such that the positional deviationamount is within a predetermined tolerance, the master reticle 46A isaligned with the stage coordinate system (X, Y). After that, apositional deviation amount between a detection center of the alignmentsensor 28 and another reference mark on the reference mark member FM isdetected, and a position of the mark on the working reticle 43 isdetected by the alignment sensor 28. With the above operation, it ispossible to expose a pattern image of the master reticle 46A at adesired position on the working reticle 43. Since only one layer may beexposed on the working reticle 43 in the present embodiment, it is notalways necessary to use the alignment sensor 28, and even if theposition of the working reticle 43 can be controlled only using themeasured value of the laser interferometer 24, it is possible to carryout the stitching exposure with high precision.

[0116] Further, the projection optical system PL of the presentembodiment is provided with a lens driving system 30 for slightly movinga predetermined lens in the projection optical system PL. When the maincontrol apparatus 7 drives the lens driving system 30 through an imagecorrecting apparatus 31, it is possible to restrict variation in imagecharacteristics such as distortion of the projection optical system PLwith respect to variation in atmospheric pressure.

[0117] Next, one example of the operation when a predetermined workingreticle is produced using the reticle designing system and the reticleproducing system will be explained with reference to flowcharts in FIGS.8A to 8C. First, in step 101 in FIG. 8A, partial design data of areticle to be produced, and identification information indicative ofportion that can be divided (portion requiring soft line controlprecision in the present embodiment) are input to the circuit designcentralized control apparatus 38 by the terminals 39 a to 39 d shown inFIG. 1. The circuit design centralized control apparatus 38 transmitsone design data of the reticle pattern obtained by collecting the entirepartial design data and identification information corresponding theretoto the reticle producing system 41. In next step 102, the proceduremanaging apparatus 40 divides the reticle pattern into M number ofexisting pattern portions and N number of newly-forming pattern portions(N and M are integers equal to one or more) based on the design data ofthe supplied reticle pattern and the identification information.

[0118] In this case, using the projection magnification β (β is ¼, ⅕ orthe like) of the light exposing section 32 shown in FIG. 1, the existingpattern portion is a pattern which is the same as a pattern of themaster reticle for already produced device reduced in size by β times.The master reticle in which the existing pattern is formed isaccommodated in the existing reticle accommodating section 35 shown inFIG. 1. Whereas, the newly-forming pattern portion is a pattern that hasnot been formed or a pattern of a device that is not formed in themaster reticle in the existing reticle accommodating section 35.

[0119]FIG. 3A shows one example of dividing method of a pattern of theworking reticle 43 to be produced. In FIG. 3A, a pattern region 47surrounded by a frame-like light shield band 44 on the working reticle43 is divided into 40 patterns comprising existing pattern portions S1to S24, newly-forming pattern portions N1 to N8 having wide areas, andnewly-forming pattern portions P1 to P8 having small area. The Xdirection and the Y direction in FIGS. 3A and 3B respectively correspondto the X direction and the Y direction in FIG. 2. In the patterns of thesame kind (i.e., S1 to S6) a boundary line of division is shown withdotted line. A typical example of the existing pattern portions S1 toS24 comprises one pattern portion or a CPU or memory formed by stitchinga plurality of pattern portions. On the other hand, an example of thenewly-forming pattern portions P1 to P3 is a wire.

[0120] In this case, the procedure managing apparatus 40 transfers the Mnumber of master reticles on which enlarged existing pattern portions S1to S24 are formed using a reticle transfer mechanism (not shown), andaccommodates the M number of master reticles in a reticle library (notshown) of the projection exposure apparatus (light exposing section 32)shown in FIG. 2.

[0121]FIG. 4 shows some of master reticles. In FIG. 4, original patternsS17B to S24B obtained by enlarging the existing pattern portions S17 toS24 with magnification of 1/β are formed in master reticles 46A to 46H.These original patterns S17B to S24B are formed by etching of lightshield film such as chromium (Cr) film. The original patterns of themaster reticles 46A and 46B are respectively surrounded by light shieldbands 56A and 56B made of chromium film, and alignment marks 64A and 64Bare formed on outer sides of the light shield bands 56A and 56B.Similarly, other master reticles are also formed with the light shieldbands and the alignment marks (not shown).

[0122] As a substrate of each of the master reticles 46A, 46B, . . . ,quartz (e.g., synthetic quartz) can be used if the exposure light of thelight exposing section 32 is KrF or ArF excimer laser or the like. Ifthe exposure light is F₂ laser light or the like, quartz in whichfluorite or fluorine is mixed can be used as the substrate. Since theexisting master reticles 46A, 47B, . . . , are repeatedly used, thepattern forming surface is provided with a pellicle comprising parallelflat plate of light transmission for preventing a foreign substance fromattaching.

[0123]FIG. 6 is a side view showing the master reticle 46A. In FIG. 6, apellicle 50 having predetermined thickness and refractive index is fixedsuch as to cover the original pattern S17B of the pattern region 48 ofthe master reticle 46A. Therefore, the projection optical system PL ofthe light exposing section 32 commonly use the pattern surface of themaster reticle 46A and the working reticle 43 while taking the thicknessof the pellicle 50 into consideration.

[0124] Next, the procedure managing apparatus 40 generates new originalpatterns having the newly-forming pattern portions N1 to N8 and P1 to P3which are enlarged with reciprocal (1/β) magnification (e.g., four timesor five times) of the projection magnification β. In steps 103 to 110 inFIG. 8A, the master reticles in which these new original patterns areformed are produced. The procedure managing apparatus 40 resets a valueof a parameter indicating order of the newly-forming pattern portions to0 (step 103), checks whether the parameter “n” reached N (step 104).When “n” did not reach N, the flow proceeds to step 105, and 1 is addedto the value of the parameter “n”.

[0125] Electron beam resist is applied to an n-th substrate of thefluorite or fluorine taken out from the substrate accommodating section36 in the cotar developer sections (C/D section) 37. The substrate istransferred to the EB pattern-forming section 33 from the cotardeveloper sections 37 through the substrate transfer section 34 (step106). A predetermined alignment mark is formed on the substrate. Designdata of the original pattern having the M number of new patternsenlarged by the procedure managing apparatus 40 is supplied to the EBpattern-forming section 33. After the EB pattern-forming section 33positions the pattern-forming position of the substrate using thealignment mark of the substrate (step 107), the EB pattern-formingsection 33 directly forms the n-th original pattern on the substrate(step 108). Then, the substrate pattern-formed by the electron beam istransferred to the cotar developer sections 37, and the electron beamresist development is carried out (step 109). The exposure beam resistof the present embodiment has characteristics to absorb the exposurelight (excimer laser light) used by the light exposing section 32.Therefore, resist pattern remained by the development can be used as anoriginal pattern as it is. Then n-th substrate after development istransferred to the reticle library of the light exposing section 32 as amaster reticle for the n-th newly-forming pattern portion (step 110).

[0126] A producing procedure of the master reticle will be explained indetail with reference to FIGS. 7A to 7C. First, as shown in FIG. 7A,electron beam resist 52 is applied to a substrate 51, the originalpattern is formed on the electron beam resist 52 under vacuum atmospherein the EB pattern-forming section 33. Thereafter, it is developed, andwhen the electron beam resist is positive, a resist pattern 52 a of aregion of a pattern region 53A that is not irradiated with exposure beamis left as the original pattern. In the present embodiment, a coloringmatter absorbing exposure light (or reflective) used in the lightexposing section 32 is included in the resist pattern 52 a. Therefore,the substrate 51 can be used as the master reticle 55A withoutsubjecting the substrate 51 to deposition of chromium film and etching.With this, there is merit that the master reticle can be produced in ashort time at low producing cost.

[0127] In this case, since the master reticle 55A does not have thedust-proofing pellicle 50 which is mounted to master reticle 46A shownin FIG. 6, if the exposure is carried out by the projection exposureapparatus shown in FIG. 2, there is an adverse possibility that defocusis generated. In order to avoid this, when the master reticle 55A isplaced on the reticle stage 17 shown in FIG. 2, it is desirable todispose a focus correcting plate 54 having the same material and samethickness of those of the pellicle 50 between the projection opticalsystem PL and the reticle stage 17 as shown in FIG. 7C. When the focuscorrecting plate 54 is not used, a position of the reticle stage 17 orthe sample stage 21 in the Z direction may be corrected such that thedefocus is compensated.

[0128] Returning to the flowchart in FIG. 8A, the N-number of masterreticles corresponding to all the newly-forming pattern portions shownin FIG. 3A can be produced by repeating the steps 105 to 110 N times.

[0129] In this case, the original patterns of the newly-forming patternportions N1 to N8 having relative large areas are respectively formed inone master reticle. However, the newly-forming pattern portions P1 to P8having small wires, a plurality of original patterns are formed in onemaster reticle as shown in FIG. 5.

[0130] As shown in FIG. 5, the original patterns P1N, P2N, P7N, P8Nhaving enlarged newly-forming pattern portions P1, P2, P7, P8 are formedin one master reticle 55A. The original patterns P3N to P6N having thenewly-forming pattern portions P3 to P6 are also formed in the P53B ofone master reticle 55B. When the plurality of original patterns areformed on the one master reticle 55A, 55B in this manner, only a desiredoriginal pattern is selected by visual field aperture at the time ofexposure. For example, the original pattern P1N is exposed to light, avisual field 48 is set such that the visual field 48 is within a lightshield band (not shown) the original pattern P1N using the movable blindof the illumination visual field aperture system 11 shown in FIG. 2 atthe time of scanning and exposure, so that a pattern other than thevisual field 48 is not exposed to light. Alignment marks (not shown) areformed also on outer side of the pattern regions of the master reticles55A and 55B.

[0131] Next, in step 111 in FIG. 8B, the procedure managing apparatus 40takes out a substrate (made of quartz in which fluorite or fluorine ismixed) for the working reticle 43 from the substrate accommodatingsection 36 shown in FIG. 1. A metal film such as chromium film ispreviously deposited on the substrate, and a mark for rough positioningis also formed. This positioning mark is not always necessary. Thesubstrate is transferred to the cotar developer sections 37, andphotoresist that is sensitive to the exposure light of the lightexposing section 32 is applied to the substrate. Next, the substrate istransferred to the projection exposure apparatus shown in FIG. 2 throughthe substrate transfer section 34, a command to carry out the stitchingexposure is sent to the main control apparatus 7 using the pluralitymaster reticles.

[0132] Information concerning positional relation between thenewly-forming pattern portion and the existing pattern portion in thepattern region 47 shown in FIG. 3A is also supplied to the main controlapparatus 7.

[0133] In reply thereto, the main control apparatus 7 pre-aligns thesubstrate with respect to the outer shape reference by the substrateloader system and then, loads the substrate onto the sample stage 21 inthe light exposing section 32. Then, positioning with respect to stagecoordinate system (X, Y) is carried out using a positioning mark on thesubstrate and the alignment sensor 28 if necessary.

[0134] Next, the main control apparatus 7 resets the parameter nindicative of order of exposure of the N number of new master reticlesto zero (step 112) and then, checks whether the parameter n reached N(step 113), adds 1 to the parameter n when the parameter n is smallerthan N (step 114), and the flow proceeds to step 115. Then, the n-thmaster reticle is taken out from the reticle library and placed on thereticle stage 17. Thereafter, positioning of the master reticle withrespect to the stage coordinate system (S, Y) and thus the substrate ofthe working reticle 43 using the alignment mark of the master reticleand the reticle alignment microscope (not shown).

[0135] Next, the flow proceeds to step 116, the main control apparatus 7control the position of the sample stage 21 such that the exposureregion on the substrate of the working reticle 43 becomes the designedexposure position of the n-th master reticle. Thereafter, the scanningand exposure are started, and a reduced image of the original pattern ofthe master reticle is exposed to light on the substrate. At that time,if the master reticle is master reticles 55A and 55B shown in FIG. 5,the visual field is switched in accordance with a pattern to betransferred, and the exposure is repeatedly carried out using one masterreticle 55A, 55B. When the stitching exposure of the n-th new masterreticle is completed in this manner, the flow proceeds to step 117 fromstep 113 shown in FIG. 8C, the main control apparatus 7 resets aparameter m indicative of exposure order of the M number of existingmaster reticles and then, checks whether the parameter m reached M (step118), adds 1 to the parameter m when the parameter m is smaller than M(step 119), and the flow proceeds to step 120. The m-th existing masterreticle is placed on the reticle stage 17 to carry out the positioningand the reduced image of the master reticle is scanned and exposed tolight at a designed position on the substrate in step 121.

[0136] If stitching exposure of all the master reticles is completed inthis manner, the flow proceeds to step 122 from step 118, and thesubstrate of the working reticle 43 is transferred to the cotardeveloper sections 37 and developed. Thereafter, the developed substrateis transferred to an etching section (not shown), and remaining resistpattern is etched as a mask (step 123). Further, the resist is peeledoff and the dust-proofing pellicle is fixed if necessary, therebycompleting the working reticle 43 shown in FIG. 3A. Further, a necessarynumber of working reticle having the same pattern as that of the workingreticle 43 can be produced in a short time only by repeating the steps111 to 123.

[0137] In the above embodiment, the original pattern formed in the EBpattern-forming section 33 is rougher than the pattern of the workingreticle 43, and the pattern to be formed is about ½ or less as comparedwith the pattern of the working reticle 43. Therefore, thepattern-forming time of the EB pattern-forming section 33 is largelyreduced as compared with a case in which all the patterns of the workingreticle 43 are directly formed. In generally, since a step and scan typeprojection exposure apparatus using a KrF or ArF excimer laser lightsource and corresponding to the minimum line width of about 150 to 180nm can be used as it is as the light exposing section 32 (projectionexposure apparatus), the number of production facilities to be newlyprepared is small, the producing costs can be reduced, and thedeveloping time of the reticle can largely be reduced.

[0138] A working reticle 43 to be produced is 9×9 inches for example,and the pattern is projected onto a wafer with reduction magnificationsuch as ¼ or ⅕ by another projection exposure apparatus. The wafer is adisc-like substrate such as semiconductor device (silicon or the like)or SOI (silicon on insulator) for example. If the reductionmagnification is set to ¼, and the minimum line width of the patternimage that is to be projected on the wafer finally is 180 to 100 nm, andthe required precision of the line width is 5%, the minimum line widthof the pattern of the working reticle 43 is 720 to 400 nm, and theworking precision is about 36 to 20 nm (1.6×10⁻⁷ to 0.8×10⁻⁷) withrespect to the entire length 230 mm. This precision can not be achievedeasily even if attempt is made to directly form the pattern itself ofthe working reticle 43 by the electron beam drawing apparatus.

[0139] Whereas, in the present embodiment, the original pattern to benewly formed by the electron beam drawing apparatus (EB pattern-formingsection 33) is an original pattern whose partial pattern of the workingreticle 43 shown in FIG. 3A is enlarged four times or five times. Whenthe projection image of the projection exposure apparatus in FIG. 2 issubstantially ideal, if the pattern-forming precision of the currentelectron beam drawing apparatus is 2.4×10⁻⁷ and the magnification of theoriginal pattern is four times, the pattern-forming precision on theworking reticle 43 is about 0.6×10⁻⁷, and required precision can beobtained on the wafer. In the present embodiment, since the originalpattern to be formed by the electron beam drawing apparatus is a patternhaving a length equal to or less than ¼ of the pattern of the workingreticle 43, a practical pattern-forming precision is further enhanced.

[0140] Although transparent working reticle 43 is to be produced in theabove embodiment, it is possible to similarly produce a reflectivereticle using a wafer such as silicon wafer as a substrate, and a mask(stencil mask) of a membrane structure using a wafer as a substrate. Thereflective reticle is used in an exposure apparatus using extremeultraviolet light (EUV light) as exposure beam for example, and the maskof membrane structure is used in an exposure beam exposure apparatus.

[0141]FIG. 3B shows a reflective reticle 45 having the same pattern asthat of FIG. 3A. In FIG. 3B, a pattern region in a light shield band 44W(made of film absorbing EUV light) of the reticle 45 using a siliconwafer as a substrate is divided into existing pattern portions S1 toS24, newly-forming pattern portions N1 to N8 and newly-forming patternportions P1 to P8. In this case, EUV light absorbing film, reflectivefilm and resist are sequentially applied to the substrate, the reducedimage of the master reticle which is the same as that in the aboveembodiment is exposed while stitching screens, and developing andpattern forming treatment are carried out, thereby producing thereflective reticle 45. A multi-layer comprising molybdenum (Mo) andsilicon (Si) which are alternately laminated is used as the reflectivefilm of EUV light when its wavelength is 13.4 nm, and a multi-layercomprising molybdenum (Mo) and beryllium (Be) is used as the reflectivefilm when the wavelength is 11.5 nm.

[0142] It is considered that the minimum line width of the pattern to beproduced by the exposure apparatus using EUV light for example is about130 to 30 nm, and if the exposure apparatus uses reduced projection ofabout ¼, the required precision of the pattern on the reflective reticle45 is about (1.2×10⁻⁷ to 0.2×10⁻⁷). If an original pattern whose reticle45 is enlarged four times for example is formed by the electron beamdrawing apparatus and a length of the master reticle is set to the sameas that of the reticle 45, the pattern-forming precision of about0.6×10⁻⁷ is obtained. Therefore, if the size of the master reticle isreduced to about ⅓ of the reticle 45, i.e., if the number of divisionsof the pattern of the reticle 45 is increased, the pattern-formingprecision of about 0.2×10⁻⁷ is obtained.

[0143] Next, in the above embodiment, since the reduced images of theplurality of master reticle are exposed while stitching screens, anexposure method for reducing influence of stitching error at theboundary portion is used. The exposure method will be explained withreference to FIGS. 9A to 9C, 10A to 10C, 11A to 11C, 12A to 12C, and 13Ato 13C. Here, the explanation will be made based on a case in which thereduced images of the patterns of the two master reticles 46A and 46Bare stitched and exposed and then, development, etching and the like arecarried out and finally, a plurality linear patterns 59 comprising metalfilms each having a predetermined line width (L1+L2) are formed as shownin FIG. 10C. The linear pattern 59 actually has the same shape as thatof the inversed reduced image of the original pattern of the masterreticle, but it is supposed that the reduction magnification is one time(with a magnification ratio of 1:1) and an erect image is projected forsimplification.

[0144]FIG. 9A shows original pattern S17 and S18 to be formed on themaster reticles 46A and 46B in corresponding to the linear pattern 59.In FIG. 9A, a first pattern 57 comprising light shield film having apredetermined width (the same as that of the linear pattern 59) and alength of (L1+ΔL) as a portion of the original pattern S17B is formed,and the first pattern 57 is connected to the light shield band 56A. Anoverlapping portion 57 a of length 2×ΔL on the side of the light shieldband 56A of the first pattern 57 is gradually spreading at angle φ. Theoptimal range of the angle φ is 30° to 60°, and in the presentembodiment, one example thereof is set to about 45°. The overlappingportion 57 a may gradually spread toward the boundary stepwisely.

[0145] The width ΔL is set to about expected maximum value of apositional deviation amount of adjacent projection images when thestitching exposure is carried out. Similarly, a portion of the otheroriginal pattern S18B is formed with a second pattern 58 comprisinglight shield film having a predetermined width and a length of (L2+ΔL)connected to the light shield band 56B. A overlapping portion 58 ahaving a length of 2×ΔL spreading at angle φ is also formed on the sideof the light shield band 56B of the second pattern 58. That is, a totalof length of the patterns 57 and 58 (L1+L2+L+2×ΔL) is formed longer thana length (L1+L2) of the linear pattern 59 by 2×ΔL.

[0146] Next, if the reduced images of the original patterns S17B andS18B are sequentially connected and exposed to light, as shown in FIG.9B, an image 56AP of the light shield band 56A and an image 57P of thefirst pattern 57 are exposed to light, and an image 56BP of the lightshield band 56B and an image 58P of the second pattern 58 are exposed tolight. At that time, if there is no positional deviation. The firstpattern 57P and the second pattern 58P are overlapped at portions of theoverlapped images 57aP and 58aP of width of 2×ΔL, and the first pattern57P and the second pattern 58P are projected on the same straight line.

[0147] If the photoresist is developed after it is exposed to light ofnormal exposure light amount, the linear pattern 59 having a boundary 59a of length (L1+L2) and width of 2×ΔL is left as a resist pattern asshown in FIG. 9C. A central portion of the boundary 59 a is thick and ofangle shape. If the resist pattern is etched as a mask, the linearpattern 59 becomes a metal film pattern of the same shape. According tothe normal exposure light amount, the boundary 59 a is remained. Tosolve this problem, the exposure light amount is increased to carry outthe over exposure. The boundary 59 a is originally extremely small whenit was designed, and in reality, the boundary 59 a becomes smaller byexposure light that wraps around. Further, the boundary 59 a can be madesmaller by optimizing angles φ of the overlapping portions 57 a and 58a. When there is no influence even if the boundary 59 a is remained dueto characteristics of device, the normal exposure light amount may beused.

[0148]FIGS. 10A to 10C show the linear pattern 59 made of metal filmobtained finally when the stitching exposure shown in FIG. 9B is carriedout with over exposure. If the exposure light amount is increasedslightly, a boundary portion 59 b becomes slightly smaller as shown inFIG. 10A, and if the exposure light amount is further increased, aboundary portion 59 c becomes further smaller as shown in FIG. 10B, andif the exposure light amount is reduced by a predetermined amount, aboundary portion whose line width is varied does not exist. Therefore,it is recommended to previously obtain such an exposure light amountthat the boundary portion does not exist by test printing or the like.With this method, even if the stitching exposure is carried out, theline width is not varied halfway, and performance of the device isenhanced.

[0149] With the over exposure, a line width of not only the boundaryportion 59 c, but also of the liner pattern 59 becomes thin in somecases. To avoid this problem, the line width of the linear pattern 59 onthe master reticle is made thicker than a designed value while takingthe over exposure light amount into consideration.

[0150] Influence of positional deviation on the boundary portion whenthe stitching exposure is carried out will be explained. FIG. 11A showsthe same original patterns S17B and 118B as those of FIG. 9A. FIG. 11Bshows the second pattern image 58P deviated laterally by 2×ΔL. In thiscase also, the linear pattern 59 that is remained after the developmentand pattern formation is brought into a state in which the boundaryportion 59 d of length of 2×ΔL is bent, the line width is not variedalmost at all and thus, the performance of the device is not variedalmost at all. Therefore, the lateral deviation amount h of the secondpattern 58P with respect to the first pattern 57P is permitted up toabout ±2×ΔL.

[0151] Further, in FIG. 9B, even if a length g of the overlappingportion between the first pattern 57P and the second pattern 58P isvaried within a range of ±2×ΔL or less, since the shape of the boundaryportion 59 a of the obtained linear pattern 59 is not varied almost atall, tolerance range of the positional deviation amount in thelongitudinal direction is about ±2×ΔL.

[0152] In order to compared with the above embodiment, an example of alinear pattern 62 obtained by stitching and exposing a pattern having nooverlapping portion is shown in FIGS. 12A to 12C and FIGS. 13A to 13C.That is, as shown in FIG. 12A, if the linear patterns 60 and 61 areoverlapped on the light shield bands 56A and 56B by a length of ΔL andsequentially exposed to light, the pattern images 60P and 61P areexposed as shown in FIG. 12B. If the image 61P is laterally deviated byΔL at that time, in the linear pattern 62 obtained after the developmentand the like, a width of the boundary portion 62 a of the length ΔL isnarrowed by ΔL as shown in FIG. 12C, and there is an adverse possibilitythat the operation speed of the device is affected.

[0153] Further, as shown in FIG. 13B, after the linear patterns 61 and61 shown in FIG. 13A are sequentially exposed such that the light shieldbands 56A and 56B are overlapped by the length ΔL, the linear pattern 62obtained by being developed is short circuited at the boundary portion62 b of the length ΔL. In such a state, the device can not operatenormally. Therefore, when the tip end is not provided with a thickoverlapping portion, if a positional deviation exceeding ΔL is generatedin the longitudinal direction, the short circuit is generated, but inthe above embodiment, tolerance of the positional deviation amount inthe longitudinal direction is increased.

[0154] Conventionally, a technique for splicing portions are madesemi-transparent and overlapped with each other is used. However,according to such a technique, there is an adverse possibility that theuneven exposure light amount is generated in a semi-transparent portion,and it is necessary to take influence of a foreign substance attached tothe semi-transparent portion into consideration. However, according tothe present embodiment, such an adverse influence need not be taken intoaccount.

[0155] Although the excimer laser light source 2 and the light exposingsection 32 are step and scan type projection exposure apparatuses in theabove embodiment, as the projection exposure apparatus, a blanket type(stepper type) projection exposure apparatus may be used.

[0156] In the EB pattern-forming section 33 in FIG. 1, the electron beamdrawing apparatus for directly forming image using exposure beam isused, a cell projection type electron beam drawing apparatus for forminga pattern with exposure beam of a predetermined shape may be used. Inthis case, there is merit that the producing time of a master reticle tobe newly prepared is shortened, and the producing time of the workingreticle is also shortened correspondingly. The above embodiment providethe reticle producing system 41 integrally provided with the EBpattern-forming section 33, the light exposing section 32 and the cotardeveloper sections 37. Instead of it, a system for connecting, through atransfer mechanism, the EB pattern-forming section 33, the lightexposing section 32 and the cotar developer sections 37 which areindependently operated.

[0157] The above embodiment up to FIG. 8C is based on a premise ofstitching exposure, but a circuit pattern to be formed on the workingreticle may be divided into function block units (i.e., a CPU, a DRAM, aSRAM, a D/A converter, an A/D converter or the like), the stitchingportion between adjacent patterns may be eliminated, or the number ofstitching portions may be reduced. Not only in the above embodiment, butalso in the following embodiments, a resist having color agent may beused to produce a master reticle without carrying out etching, and thismaster reticle may be used, or a conventional master reticle may beused.

[0158] Next, a second embodiment of the invention will be explained withreference to FIGS. 14 to 18B. In the present embodiment, the inventionis applied to a case in which one working reticle in which an enlargedpattern of a layer of a semiconductor device is formed is produced byexposing, on a predetermined substrate, images of patterns of aplurality of master reticles using a stepper type (blanket type)projection exposure apparatus while stitching screens.

[0159]FIG. 14 shows a projection exposure apparatus used in the presentembodiment. In FIG. 14, as an exposure light source 201, an ArF excimerlaser (oscillation wavelength is 193 nm) having a half-width ofoscillation spectrum of about 1 pm or less is used. Another laser lightsource such as a KrF excimer laser (wavelength is 248 nm) or an F₂ laser(wavelength is 157 nm) may be used as the exposure light source 201 orsolid laser such as YAG laser or an emission line lamp such as mercurylamp may be used.

[0160] Illumination light IL for exposure emitted from the exposurelight source 201 passes through a beam shaping optical system 202 and avibrating mirror 203 for preventing speckle, and enters a fly eye lens204 as an optical integrator (homogenizer). An aperture variable plate205 (corresponding to switching revolver 5) of an illumination system isrotatably disposed on an ejection surface of the fly eye lens 204 by adriving motor 205 a. A circle opening aperture 205 b for normalillumination, a band-like opening aperture 205 c for band-likeillumination, a small circle opening aperture 205 d for small coherencefactor (α value), and an opening aperture 205 e for deformationillumination comprising a plurality eccentric small openings aredisposed around a rotation shaft of the aperture variable plate 205.More illumination opening aperture (α aperture) may be provided ifnecessary. A main control system 212 for controlling the operation ofthe entire apparatus rotates the aperture variable plate 205 through thedriving motor 205 a to dispose the predetermined illumination openingaperture on the ejection surface of the fly eye lens 204 so thatnecessary illumination condition can be set.

[0161] The illumination light IL that passed the illumination systemopening aperture of the ejection surface of the fly eye lens 204illuminates a reticle blind (variable visual field aperture) 207 througha relay lens 206. The reticle blind 207 includes four movable blades asone example, a position and a size of a rectangular opening surroundedby these movable blades can be varied under control of the main controlsystem 212. However, the position and the size thereof are constant whenone wafer is exposed to light. The illumination light IL that passed theopening of the reticle blind 207 passed through a relay lens 208 and acondensor lens 209, and illuminates a rectangular (square in the presentembodiment) illumination region 210 as a visual field of a patternsurface (lower surface) of a reticle to be exposed (master reticle RA inthe present embodiment). The disposing surface of the reticle blind 207is conjugate with the pattern surface, and a position and a size of theillumination region 210 are defined by an opening of the reticle blind207.

[0162] A pattern in the illumination region 210 of the master reticle RAis reduced in size and projected on an exposure light region 230 on aglass substrate 218 on which photoresist to be exposed is applied with apredetermined projection magnification β (β is ¼, ⅕ or the like) througha projection optical system PL2. The projection optical system PL2 is arefractive system. When vacuum ultraviolet region light having awavelength of about 200 nm or less such as the ArF excimer laser lightis used, it is preferable that the projection optical system PL2 is acatadioptric system in order to reduce the chromatic aberration becausethere is few glass material having excellent transmittancy. In thefollowing explanation, the Z axis is in parallel to an optical axis AXof the projection optical system PL2, the X axis is in parallel to thepaper sheet of FIG. 14 within a plane intersecting with the Z axis, andthe Y axis is perpendicular to the paper sheet of FIG. 14.

[0163] The master reticle RA is held on a reticle stage 214. The reticlestage 214 is disposed on a reticle base 215 such that the master reticleRA can move within a predetermined range in the X direction, the Ydirection and the rotation direction by a linear motor. A moving mirror16m fixed to the reticle stage 214 is irradiated with triaxial laserbeam for example by means of a laser interferometer 216, and the Xcoordinate, the Y coordinate and the rotation angle of the reticle stage214 are measured by the laser interferometer 216. These measured valuesare supplied to the main control system 212 and a reticle state drivingsystem 217. The reticle state driving system 217 controls the movingspeed and the position of the reticle stage 214 based on the controlinformation from the measured value and the main control system 212.

[0164] On the other hand, the glass substrate 218 is absorbed and heldon a substrate holder (not shown), the substrate holder is fixed on asample stage 219, and the sample stage 219 is fixed on a wafer stage220. The wafer stage 220 continuously moves the sample stage 219 on awafer base 221 in the X direction and the Y direction, and stepwiselymoves the sample stage 219 in the X direction and the Y direction. Theprojection exposure apparatus of the present embodiment can hold a wafersuch as a silicon wafer and expose reduced images of reticle patterns onshoot regions. When the wafer is exposed, a substrate holder (not shown)on the sample stage 219 is replaced by a wafer holder.

[0165] In the wafer stage 220, a Z stage mechanism for controlling aposition of the sample stage 219 in the Z direction (focus position) andan inclination angle is also incorporated. A defocus amount from animage surface in a plurality of measurement points of a surface of theglass substrate 218 is measured by an oblique-incidence type autofocussensor (not shown) disposed on a side surface of the projection opticalsystem PL2. At the time of exposure, the focus position and theinclination angle of the glass substrate 218 are controlled in anautofocus manner such that the defocus amount comes within thetolerance.

[0166] A moving mirror 22m fixed on a side surface of the sample stage219 is irradiated with triaxial laser beam from an external laserinterferometer 222, the laser interferometer 222 measures the xcoordinate, the Y coordinate and the rotation angle of the sample stage219 (glass substrate 218), and the measured values are supplied to awafer driving system 223 and the main control system 212. The waferdriving system 223 drives the wafer stage 220 in the X direction and theY direction based on the measured value of the laser interferometer 222and the control information from the main control system 212. Designdata of the working reticle to be produced and the like are stored in anexposure data file 213 connected to the main control system 212.

[0167] At the time of exposure, the master reticle on the reticle stage214 is replaced, the wafer stage 220 is stepwisely moved to position theglass substrate 218 and then, the reduced image of the pattern of thereplaced master reticle is exposed to light on the glass substrate 218.This operation is repeated in a step and repeat manner, and one image asa whole of a pattern of one reticle is transferred on the glasssubstrate 218. In the present embodiment, as will be explained later,since a boundary region of images of patterns of adjacent masterreticles are exposed to light twice, the reticle stage 214 and the waferstage 220 are moved synchronously in each the exposure operation.

[0168] Before such an exposure is carried out, it is necessary to alignthe master reticle and the glass substrate 218 with high precision. Forthis purpose, a reference mark member 224 (corresponds to the referencemark member FM in FIG. 1) is fixed to the sample stage 219 in thevicinity of the glass substrate 218. As shown in FIG. 16,two-dimensional reference marks 231A and 231B are formed on thereference mark member 224. In FIG. 16, a pair of image processing typereticle alignment microscopes (“RA microscopes” hereinafter) 232A and232B are disposed above the master reticle RA at a predetermineddistance from each other in the X direction. The RA microscopes 232A and232D picks up images of the alignment marks 242A and 242B on the masterreticle RA using illumination light having the same wavelength as thatof the illumination light IL through a mirror (not shown) and at thesame time, picks up images of reference marks 231A and 231B on thereference mark member 224 through the projection optical system PL2.Image signals of the RA microscopes 232A and 232B are supplied to analignment signal processing system 226 in FIG. 14, the alignment signalprocessing system 226 calculates positional deviation amounts of thealignment marks 242A and 242B with respect to the images of thereference marks 231A and 231B, and the positional deviation amounts aresupplied to the main control system 212.

[0169] In FIG. 14, an image processing type alignment sensor 225 fordetecting positions of the predetermined alignment marks 234A and 234B(see FIG. 15) on the glass substrate 218 is disposed on the side surfaceof the projection optical system PL2. An image signal of the alignmentsensor 225 is also supplied to the alignment signal processing system226. The alignment signal processing system 226 processes the imagesignal and detects a positional deviation amount of the alignment markwith respect to a predetermined detection center, and supplies thepositional deviation amount to the main control system 212. A referencemark (not shown) for the alignment sensor 225 is formed on the referencemark member 224. Using the reference mark, a distance (base line amount)between a center (exposure center) of the pattern image of the masterreticle to be exposed and the detection center of the alignment sensor225 is previously obtained, and is stored in the exposure data file 213.When exposure for producing the working reticle is carried out as in thepresent embodiment, the alignment sensor 225 is not always necessary.

[0170] By exposing the reduced images of patterns of the plurality ofmaster reticles while stitching screens, an image of one reticle patternas a whole is transferred onto the glass substrate 218, and one workingreticle is produced. For this purpose, a reticle library 227 is disposedon a side surface of the reticle stage 214 such that the reticle library227 can vertically move by means of a slide apparatus 229, and N number(N is an integer equal to two or more) of master reticles R1, R2, . . ., RN are placed on a plurality of shelves of the reticle library 227. Areticle loader 245 for exchanging reticles between the reticle library227 and the reticle stage 214 is also disposed. The main control system212 controls the operation of the slide apparatus 229 and the reticleloader 245, thereby exchanging the master reticle on the reticle stage214.

[0171]FIG. 15 shows a pattern arrangement of the working reticle WR thatis finally produced. In FIG. 15, a direction of the working reticle WRis shown in a state in which the working reticle is placed on the samplestage 219 in FIG. 14. A pattern region surrounded by a rectangularframe-like light shield band 233 is set on the glass substrate 218 ofthe working reticle WR. In this pattern region, rectangular partialpattern regions S1, S2, S3, . . . , SN are set at predetermineddistances from each other and at a predetermined pitch in the Xdirection and the Y direction (the same pitch in the presentembodiment), and a predetermined circuit pattern is formed in each ofthe partial pattern regions S1 to SN. A predetermined circuit pattern isformed also in each of the boundary regions 235 between the partialpattern regions S1 to SN. A pair of alignment marks 234A and 234B areformed such as to sandwich the light shield band 233 in the X direction.In the present embodiment, the alignment marks 234A and 234B are formedsubstantially at the same time when the reticle pattern is formed, butthe alignment marks 234A and 234B may be previously formed before thereticle pattern is formed.

[0172] An outline of the producing procedure of the working reticle WRin the present embodiment is as follows. That is, if the projectionmagnification of the projection exposure apparatus for carrying out theexposure using the working reticle WR is defined as α (α is ¼, ⅕ of thelike for example), a circuit pattern in the light shield band 233 inFIG. 15 having a pattern of a predetermined layer of a semiconductordevice or the like that is enlarged 1/α times (e.g., four times, fivetimes or the like) is designed in a computer, and the circuit pattern isdivided into N number of reticle patterns around the partial patternregions S1 to SN. At that time, the circuit pattern in the boundaryregion 235 is formed such as to overlap the adjacent reticle pattern.The N number of reticle patterns are further enlarged 1/β times (β isprojection magnification of the projection exposure apparatus in FIG.14), and the enlarged patterns are formed on the corresponding glasssubstrates using the electron beam drawing apparatus, thereby producingthe N number of master reticles R1 to RN shown in FIG. 14.

[0173] Thereafter, a light shield film such as chromium film is formedon the glass substrate 218 shown in FIG. 14, the photoresist is appliedon the light shield film and then, the glass substrate 218 is placed onthe sample stage 219 of the projection exposure apparatus. The reducedimages of patterns of the master reticles R1 to RN are sequentiallyexposed to light in regions around the partial pattern regions S1 to SNshown in FIG. 15. Then, the development step, the etching step and thelike are carried out, thereby producing the working reticle WR. At thattime, in the present embodiment, since the reduced images of thepatterns of the master reticles R1 to RN formed by the electron beamdrawing apparatus are transferred onto the glass substrate 218,influence caused by the patern-forming error is reduced into 1/β ascompared with a case in which a circuit pattern on a working reticle isdirectly formed by the electron beam drawing apparatus like the priorart, and the circuit pattern of the working reticle WR is formed withextremely high precision. Further, a line width of each the circuitpatterns of the master reticles R1 to RN is about 1/β times of that ofprior art, the pattern-forming time of the electron beam drawingapparatus can be shortened, and even when a plurality working reticlesare produced, patterns of the master reticles R1 to RN only may betransferred. Therefore, it is possible to largely shorten the producingtime of a plurality working reticles as a whole. Further, of the masterreticles R1 to RN, those having the same pattern can be the same, theproducing time of the master reticles can further be shortened.

[0174] The master reticle of the present embodiment may be producedusing the reticle producing system 41 in the first embodiment (FIG. 1).A master reticle may be produced using resist including coloring matterto eliminate the etching treatment. In portions (stitched portions) ofthe master reticles corresponding to the boundary region 235 of theworking reticle, exposure is carried out twice. Therefore, in order touniform the exposure light amount, an outside portion of the linearpattern may previously be tapered.

[0175] When the reduced images of the patterns of the master reticles R1to RN are exposed on the glass substrate 218 shown in FIG. 15, thereduced images of the patterns of the two master reticles are exposed tolight twice in the boundary region 235. To explain this concretely,master reticles corresponding to two partial pattern regions SA and SBdisposed adjacent to each other on the central portion of the glasssubstrate 218 are defined as master reticles RA and RB. In the masterreticle RA, rhombus overlapping portions 237A, 238A, 239A and 240A areformed such that they are in contact with four sides of a central squaresingle exposure portion 236A. A light shield band 241 is formed such asto surround the overlapping portions 237A to 240A. A circuit pattern onthe working reticle WR is enlarged 1/β times is formed on each of thesingle exposure portion 236A and the overlapping portions 237A to 240A.A pair of alignment marks 242A and 242B are formed outside of the lightshield band 241 with a predetermined positional relation with respect tothe single exposure portion 236A.

[0176] Similarly, also in the master reticle RB, a circuit pattern onthe working reticle WR is enlarged 1/β times and formed in each of theoverlapping portions 237B to 240B which are in contact with a centralsingle exposing portion 236B and four sides thereof. Alignment marks242A and 242B are formed outside of the light shield band 41 surroundingthe overlapping portions 237B to 240B with a predetermined positionalrelation with respect to the single exposure portion 236B. A pattern ofthe left overlapping portion 237A of the one master reticle RA is thesame as a pattern of the right overlapping portion 239B of the othermaster reticle RB. Linear patterns shown with oblique lines formed inthe master reticles RA and RB in FIG. 15 are one example of the circuitpattern, and in reality, a finer pattern is formed.

[0177] Reduced images of the master reticles RA, RB are projected onregions around the partial pattern regions SA, SB. As a result, an image236AP of a single exposure portion 236A and a result, an image 236BP ofa single exposure portion 236B are projected in the partial patternregions SA, SB, respectively, and an image 237AP of the overlappingportion 237A and an image 237BP of the overlapping portion 237B areoverlapped and projected in a rhombus boundary 35AB between the partialpattern region SA and SB. An image is inverted and projected by theprojection optical system PL2 shown in FIG. 14. An image 238AP of anoverlapping portion 238A and an image 240CP of an overlapped of themaster reticle corresponding to the partial pattern region SC areoverlapped and projected in the boundary region 235AC between thepartial pattern region SA and the partial pattern region SC in the Ydirection. Similarly, pattern images of two master reticles areoverlapped and projected in another boundary region 235.

[0178] When the pattern images of two master reticles are overlapped andprojected in the boundary region 235 in this manner, the stitching errorin the boundary region 235 can be reduced, but if the images are merelyoverlapped and exposed to light, the exposure light amount in theboundary region 235 is twice as great as the exposure light amount inthe partial regions S1 to SN, and uniformity of the exposure lightamount distribution can not be obtained. In order to make the exposurelight amount in the boundary region 235 equal to that in the partialpattern regions S1 to SN, and make the distribution flat, when thepattern images of the master reticles R1 to RN are exposed to light, theexposure light amount of the overlapping portion is set smaller asapproaching the periphery. A manner to expose the pattern image of theone of master reticle RA will be explained with reference to FIGS. 16 to18.

[0179]FIG. 16 is a perspective view of an essential portion showing astate in which a pattern image of the master reticle RA is exposed tolight using the projection exposure apparatus shown in FIG. 14. In FIG.16, it is assumed that up to the partial pattern region upstream fromthe partial pattern region SA on the glass substrate 18 has already beenexposed to light. Immediately after the master reticle RA is placed onthe reticle stage 214 shown in FIG. 14, positioning of the sample stage219 (wafer stage 220 in FIG. 14) is carried out such that centers of thereference marks 231A and 231B on the reference mark member 224substantially coincide with a center (optical axis) of the exposureregion 230 of the projection optical system PL2. Then, positionaldeviation amounts of the alignment marks 242A and 242B of the masterreticle RA with respect to the images of the reference marks 231A and231B is detected, and the positioning of the reticle stage 214 shown inFIG. 14 is carried out such that the positional deviation amounts aresymmetric with respect to each other and become minimum. With thisoperation, the center (exposure center) of the pattern image of themaster reticle RA is positioned with respect to the centers of thereference marks 231A and 231B. That is, the alignment of the reticle ofthe master reticle RA is completed.

[0180] In this case, since the positional relation between the partialpattern regions S1 to SN is previously stored in the exposure data file213, if a moving amount of the reference mark member 224 is defined as areference when the first partial pattern region S1 on the glasssubstrate 218 shown in FIG. 16 as one example is exposed to light, amoving amount of the reference mark member 224 (wafer stage 220 in FIG.14) for bringing the centers of the subsequent partial pattern regionsS2 to SN into coincidence with the exposure center can be calculated.Further, it is also possible to previously form the alignment marks 234Aand 234B on the glass substrate 218 shown in FIG. 16, and to detectpositions of the alignment marks 234A and 234B using the alignmentsensor 225, thereby bringing the centers of the subsequent partialpattern regions S2 to SN into coincidence with the exposure center.

[0181] The main control system 212 first aligns the center of thepartial pattern region SA with the exposure center by driving the waferstage 220 based on the moving amount of the wafer stage 220 with respectto the partial pattern region SA. Then, by driving the reticle stage 214in a direction crossing the X axis in a clockwise direction at 45°, thesingle exposure portion 236A of the master reticle RA is inscribed withsides of the illumination region 210 in the +X direction and the −Ydirection. At that time, the overlapping portions 237A and 240A areinscribed with sides of the illumination region 210 in the −X directionand +Y direction. At this stage, the irradiation of the illuminationlight IL is not yet started. Further, the partial pattern region SA isinscribed with the sides of the exposure region 230 in the −X directionand the +Y direction as shown in FIG. 16 by driving the wafer stage 220by β times (β is projection magnification) of the moving amount of thereticle stage 214. Then, the irradiation of the illumination light IL isstarted, the master reticle RA is allowed to move at a constant speedVRT in a direction (a direction of arrow 243R) crossing the Y axiscounterclockwisely through 45°, and in synchronously with this, theglass substrate 218 is allowed to move at a speed β×VRT in a directionof an arrow 243W opposite from the arrow 243R. When the overlappingportions 238A and 239A of the master reticle RA are inscribed with thesides of the illumination region 210 in the −Y direction and +Xdirection, the illumination of the illumination light IL is stopped, andthe synchronous moving of the master reticle RA and the glass substrate218 is also stopped.

[0182] FIGS. 17A1, 17B1 and 17C1 show a state in which the masterreticle RA moves in a direction of arrow 243R with respect to theillumination region 210. FIGS. 17A1, 17B1 and 17C1 show a state in whichthe glass substrate 218 moves in a direction of arrow 243W with respectto the exposure region 230 in synchronous with the moving. Size of eachof the FIGS. 17A2, 17B2 and 17C2 is actually β times of that of FIGS.17A1, 17B1 and 17C1.

[0183] As can be seen from FIG. 17A1, if a width of the single exposureportion 236 of the master reticle RA in the X direction is defined asL5, and widths of the overlapping portions 237A and 239A in the Xdirection are commonly defined as L4, and a width of the illuminationregion 210 in the X direction is defined as L3, the width L3 of theillumination region 210 is the sum of the width L5 of the singleexposure portion 236A and the width L4 of one of the overlappingportions 237A as shown in the following equation:

L3=L5+L4  (4)

[0184] Similarly, a width of the illumination region 10 in the Ydirection is the sum of a width of the single exposure portion 236A inthe Y direction and a width of the one overlapping portion 240A in the Ydirection. As shown in FIGS. 17A1 to 17C1, the master reticle RA movesin the X direction with respect to the exposure light region 210 by thewidth L4 of the overlapping portion 237A in the X direction, and movesin the Y direction by a width L6 (L6=L4 in the present embodiment) ofthe overlapping portion 240A in the Y direction. As a result, as shownin FIGS. 17A2 to 17C2, on the glass substrate 218, the image 236AP ofthe single exposure portion 236A is exposed to light on the partialpattern region SA, and the images 237AP to 240AP of the overlappingportions 237A to 240A are exposed to light such that they are in contactwith the image 236AP. The image 236AP is always exposed to light, butthe exposure time of the images 237AP to 240AP in the periphery of theimage 236AP at their inner sides is longer, and the exposure time of theimages 237AP to 240AP at their outer sides is sorter. Therefore, asshown in FIG. 17C2, on the glass substrate 218 after the exposure iscompleted, a distribution of the accumulated exposure light amount on across section along a line AA crossing the image 236AP in the Xdirection draws a slop at its end portion. That is, the distribution ofthe accumulated exposure light amount draws a trapezoid in which theoverlapping portions are inclined as shown with a curved line 244A inFIG. 18A.

[0185] In FIG. 18A, a lateral axis shows a position on the glasssubstrate 218 in the X direction, and a vertical axis shows theaccumulated exposure light amount Exposure control apparatus 1 at aposition X. Similarly, a distribution of the accumulated exposure lightamount on the cross section along a line BB crossing the image 236APshown in FIG. 17C2 in the Y direction also draws a trapezoid like thecurved line 244A in FIG. 10A.

[0186] In the present embodiment, in FIG. 16, exposure is carried outsuch that a trapezoidal accumulated exposure light amount distributionin the X direction and the Y direction can be obtained also in regionssandwiching the partial pattern region SA on the glass substrate 218.Therefore, accumulated exposure light amount distributions on theopposite sides of the accumulated exposure light amount distributionshown with a curved line 244A in FIG. 18A also draw trapezoidal shapes,and a distribution of the accumulated exposure light amount Excimerlaser light source 2 on the glass substrate 218 after images of all themaster reticles R1 to RN are exposed to light is flat as shown in FIG.18B. Similarly, a distribution of the accumulated exposure light amountin the Y direction is also flat. In the present embodiment, exposuretime with respect to each of the master reticles R1 to RN is set suchthat a maximum value of the trapezoidal accumulated exposure lightamount distribution such as the curved line 244A, i.e., a value of theaccumulated exposure light amount Excimer laser light source 2 shown inFIG. 18B becomes an appropriate exposure light amount for photoresistapplied on the glass substrate 218. With this setting, the accumulatedexposure light amount after the images of the master reticles R1 to RNare exposed to light on the glass substrate 218 in FIG. 15 becomes aflat appropriate exposure light amount in both the partial patternregions S1 to Sn and the boundary region 235, and high resolution can beobtained also in the boundary region 235 after development.

[0187] Further, in the present embodiment, in FIG. 16, alignment of eachmaster reticle is carried out using the RA microscopes 232A, 232B andthe reference mark member 224. Therefore, in the boundary region 235ABthat is in contact with the partial pattern region SA shown in FIG. 15,the image 237AP of the overlapping portion 237A and the image 239BP ofthe overlapping portion 289B are overlapped with high precision, and inthe boundary region 235AC that is in contact with the partial patternregion SA, the image 238AP of the overlapping portion 238A and the image240CP of the other master reticle are overlapped with high precision.Therefore, the stitching error in the entire boundary region 235 isreduced.

[0188] In the present embodiment, since the reticle blind 207 shown inFIG. 14 is the same as the reticle blind for a normal projectionexposure apparatus, even if the aperture variable plate 205 is rotatedto switch the illumination conditions, the accumulated exposure lightamount distribution of each the master reticle on the glass substrate218 is of trapezoidal shape, and a flat accumulated exposure lightamount distribution as a whole can be obtained.

[0189] In order to expose a device of a line and space pattern (L/Spattern) of a width of 30 to 180 nm in the future, it is necessary touse a working reticle on which an L/S pattern of a width of 120 to 800nm is formed. According to the above embodiment, it is possible toproduce such a working reticle in a short time with high precision. Evenif the glass substrate 18 is 9×9 inches in size, the working reticle canbe produced with high precision. As a projection exposure apparatus forproducing the working reticle, in order to produce an L/S pattern havinga width of 150 to 180 nm for producing a normal semiconductor device, aprojection exposure apparatus using an excimer laser light source suchas a KrF excimer laser (wavelength is 248 nm) or an ArF excimer laser(wavelength is 193 nm) can be used. Therefore, there is almost noapparatus that must be newly developed, and this is advantageous interms of producing cost.

[0190] Next, a third embodiment of the invention will be explained withreference to FIGS. 14, 19A to 21C2. Like the second embodiment, in thepresent embodiment also, one working reticle is produced by exposingimages of patterns of a plurality of master reticles on predeterminedsubstrates while stitching screens. The third embodiment is differentfrom the second embodiment in that a scanning exposure type projectionexposure apparatus is used as the exposure apparatus.

[0191] That is, in a step and scan type projection exposure apparatus asthe scanning type exposure type apparatus used in the presentembodiment, the reticle stage 214 has a function for continuously movingthrough a length exceeding a width of the pattern region of the masterreticle in the X direction while the scanning direction is the Xdirection. Further, the illumination region set on the master reticle RAby the reticle blind 207 becomes a rectangular region that is thin andlonger in a non-scanning direction (Y direction) intersecting with thescanning direction, and the exposure region by the projection opticalsystem PL2 is also rectangular. According to a basic operation, thereticle stage 214 is driven, the master reticle is moved at a constantspeed VR in the +X direction (or −X direction) with respect to theillumination region, in synchronous with this movement, the wafer stage220 is driven, and the glass substrate is moved at a speed β×VR in the−X direction (or +X direction) with respect to the exposure region. Whenthis scanning exposure is started or completed, a movable blind 211shown with a phantom line is disposed close to the reticle blind 7. Themovable blind 211 is driven in synchronous with the reticle stage 214 bythe reticle state driving system 217. The other structures are the sameas those of the second embodiment.

[0192] Even when the scanning and exposure are carried out and thescreens are stitched in this manner, like the case of the workingreticle WR in FIG. 15 in order to reduce the stitching error, images ofoverlapping portions of two master reticles are overlapped and exposedin a boundary region between the adjacent two partial pattern regions.Further, in order to uniform the exposure light amount distribution, inthe overlapping portions, the exposure light amount is set smaller asapproaching its outer side.

[0193]FIGS. 19A to 19F are explanatory diagrams when a reduced image ofa predetermined master reticle 251A is transferred onto the glasssubstrate 259 in a scanning exposure manner using the above projectionexposure apparatus. In FIG. 19A, the illumination region 210S that isthick and longer in the Y direction is irradiated with illuminationlight at the time of exposure. In the pattern region 255 of the masterreticle 251A, the overlapping portions 253 and 254 are disposed such asto sandwich the central single exposure portion 252 in the X direction,and the images of the patterns in the overlapping portions 253 and 254are overlapped with an image of a pattern of the overlapping portion ofanother master reticle (not shown). Therefore, in order to obtain a flataccumulated exposure light amount as a whole, it is necessary to obtaina trapezoidal exposure light amount distribution by lowering theexposure light amount as approaching the outer side when the images ofpatterns of the overlapping portions 253 and 254.

[0194] One example of exposure operation for obtaining the trapezoidalexposure light amount distribution in the scanning exposure manner usingthe reticle blind having a normal opening as in the present embodimentwill be explained. First, in FIGS. 19A and 19B, a width of the singleexposure portion 252 in the Y direction (non-scanning direction) isdefined as L1, a width of the overlapping portions 253 and 254 in the Ydirection is defined as L, a width of the illumination region 210S inthe Y direction is defined as L2, and a width of the illumination region210S in the X direction (scanning direction) is defined as H. Then, thewidth L2 of the illumination region 210S in the Y direction is the sumof the width L1 of the single exposure portion 252 and the width L ofthe overlapping portion 253 as follows.

L2=L1+1  (5)

[0195] Then, in order to transfer the image of the pattern of the masterreticle 251A onto the glass substrate 259 in FIG. 19F in the scanningexposure manner, first, like the second embodiment, the master reticle251A and the glass substrate 259 are aligned with each other. Then, theirradiation of the illumination light in the illumination region 210S isstarted and as shown in FIGS. 19A to 19E, the master reticle 251A isallowed to move at a constant speed VR in the −X direction (or +Xdirection). Further, with this movement, the master reticle 251A isvibrated with at amplitude of L in the Y direction (non-scanningdirection) such that the master reticle 251A does not project outwardfrom the overlapping portions 253 and 254 as shown with an arrow 256.The cycle TR of the vibration satisfies the following condition usingone or higher integer n.

TR=H/(n×VR)  (6)

[0196] This means that the master reticle 251A is vibrated n times inthe Y direction while the master reticle moves by a width H of theillumination region 210S in the X direction. FIGS. 19A to 19E shows acase in which n=1. As a result, in a system in which the master reticle251A is at a rest, the center of the illumination region 210 movesrelative to the master reticle 251A along sinusoidal wave along a locus257 shown with dotted line in FIG. 19A. Further, since the glasssubstrate 259 moves in the opposite direction from the master reticle251A with speed ratio of projection magnification β, in a system inwhich the glass substrate 259 is at a rest, the illumination region 230Smoves relative to the glass substrate 259 along a locus 269 shown withdotted line in FIG. 19F. With this, a reduced image of the singleexposure portion 252 is exposed in the partial pattern region 260A abovethe glass substrate 259, and reduced images of the overlapping portions253 and 254 are exposed in the boundary regions 261A and 162A.

[0197] A distribution of an accumulated exposure light amount Exposurecontrol apparatus 1 at a cross section along a line FF that is inparallel to the Y direction above the glass substrate 259 in FIG. 19after the scanning and exposure are completed forms a trapezoidal shapethat is gradually lowered at the overlapping portions 261A and 262A asshown with a curved line 258A in FIG. 20. In this also, the accumulatedexposure light amount around the left and right partial pattern regionsalso shows trapezoidal shape that is gradually lowered at theoverlapping portion as shown with curved lines 258B and 258D. Therefore,the accumulated exposure light amount becomes uniform and flat as awhole, the stitching error is reduced, and high resolution can beobtained.

[0198] After the scanning and exposure in the present embodiment asshown with the curved line 266 a in FIG. 21A, in order to obtain acompletely trapezoidal exposure light distribution, in the system inwhich the glass substrate 259 is at a rest, as shown with a locus 263 inFIG. 21A1, it is preferable that the exposure region 230S moves along atriangular waveform. At that time, the exposure light amountdistributions in adjacent regions are as shown with the curved line266B, and a flat exposure light amount distribution shown with astraight line 266 can be obtained.

[0199] However, in reality, as shown with a locus 264 shows with a solidline in FIGS. 21B1 or a locus 265 shown with a solid line in FIG. 21C1,the exposure region 230S may be moved in a state in which the exposureregion 230S is folded into sinusoidal wave shape or reversed sinusoidalwave relative to the glass substrate (special control having existingprobability at peripheral portion). When the exposure region 230S ismoved along the sinusoidal wave, accumulated exposure light amount thatis varied in the form of the sinusoidal wave at the adjacent oppositeend regions shown with the curved lines 267A and 267B in FIG. 21B2, anda flat exposure light amount distribution as a whole as shown with astraight line 267 can be obtained. On the other hand, when the exposureregion 230S is moved along the reversed sinusoidal wave, as shown withthe curved lines 268A and 268B in FIG. 21C2, an accumulated exposurelight amount distribution in which the adjacent opposite ends are variedin a state in which the sinusoidal wave is reversed can be obtained.

[0200] In order to move the master reticle 251A and the glass substrate259 with high precision along the substantially sinusoidal wave likelocus, the reticle stage 214 and the wafer stage 220 in FIG. 14 aredriven with forward control, and only remaining error monitored by thelaser interferometers 216 and 222 is corrected by feedback control. Whenit is difficult to achieve the synchronous control and vibration controlfor scanning and exposure using the same actuator, another actuator maybe provided. In such a case, it is preferable that a counter weightmechanism and a reaction canceling mechanism are mounted to each of theactuators so that the actuators do not affect each other.

[0201] Although a case in which the overlapping portions are provided inthe non-scanning direction in the above embodiment, the overlappingportions can be overlapped two-dimensionally and exposed in the scanningand exposing manner as shown in FIG. 15. For this purpose, a width ofthe illumination region is controlled using the movable blind 211 shownin FIG. 14 or illumination itself of the illumination light iscontrolled at the time of starting and completing in the scanningdirection.

[0202] The exposure method of the third embodiment may be applied to acase in which a reticle is produced in the first embodiment.

[0203] Except portions concerning FIGS. 9A to 13C in the firstembodiment, “stitching exposure” in each of the embodiment has nothingto do with the presence or absence of stitched portions of the adjacentpatterns, i.e., pattern portions to be actually overlapped. In otherwords, when a first region on a substrate to which a first pattern is tobe transferred and a second region on a substrate to which a secondpattern is to be transferred are partially overlapped, it is called“stitching exposure” irrespective of the presence or absence of patterns(stitching portions) to be actually overlapped.

[0204] In each of the embodiments, a plurality of master reticles may beplaced on the reticle stage, and a required master reticle may moved tothe exposure position by driving the reticle stage. With this design,the exchanging time of the master reticle can be shortened. Especially,in the case of the scanning exposure type exposure apparatus, aplurality master reticles may be arranged and held on the reticle stagealong a direction (scanning direction) along which the master reticle ismoved at the time of scanning and exposing.

[0205] Further, although the fly eye lens is used as the opticalintegrator (homogenizer) in each of the above embodiments, a rodintegrator may be used instead, or two or more fly eye lenses and or rodintegrators may be disposed. In order to change the illuminationconditions, the switching revolver 5 (FIG. 2) or the aperture variableplate 205 (FIG. 14) is used in the embodiment, but instead of them ortogether with them, an optical element (axi-con, zoom lens or the like)disposed closer to the light source than the optical integrator may bemoved to change the intensity distribution of the illumination light.The projection optical system may be of refractive, reflective, orcatadioptric.

[0206] In each of the above embodiments, the working reticle may be anyof reflective type or transparent type, a material of the substrate isnot limited to synthetic quartz, quartz doped with, fluorine, andsilicon wafer, and may be arbitrary material. The size of the substratematerial is not limited to 6×6 inches, or 9×9 inches.

[0207] Although a case in which the transparent working reticle forprojection exposure apparatus using ultraviolet light is produced ineach of the above embodiments, the present invention cal also be appliedto produce a reflective type working reticle for an exposure apparatususing extreme ultraviolet light (EUV light) having wavelength of about 5to 50 nm such as soft X-ray. The invention can also be applied toproduce an actually exposing mask of a membrane structure for theelectron beam drawing apparatus.

[0208] As an exposure apparatus used for producing the above workingreticle, in addition to the optical type projection exposure apparatus,a cell projection type exposure beam exposure apparatus for carrying outthe exposure by deviating exposure beam can be used. In this exposurebeam exposure apparatus, since aberration is generated when the exposurebeam is deviated, exposure may be carried out only in a narrow region inthe non-scanning direction in some cases. In such a case, in the aboveembodiment, the mask and the substrate move in the non-scanningdirection in synchronously, and it is unnecessary to drive the apertureportion and the cell portion in synchronously for shaping the exposurebeam into the cell. Therefore, there is merit that exposure can becarried out in a wide region in the non-scanning direction with a simplestructure.

[0209] When a semiconductor device or the like is produced, in aprocedure for exposing a circuit pattern in each shot regions above awafer for example, the invention can also be applied to expose reducedimages of a reticles while stitching screens. With this feature, it ispossible to produce a device having excellent response speed and highfunction.

[0210] As the exposure apparatus of the above embodiment, the inventionalso can be applied to a proximity exposure apparatus for bringing amask and a substrate into close contact with each other to expose apattern of the mask without using a projection optical system.

[0211] The uses of the exposure apparatus are not limited to an exposureapparatus for producing a mask or a semiconductor device, and theinvention can widely be applied to an exposure apparatus for a liquidcrystal display or a plasma display that exposes liquid crystal displayelement pattern on a rectangular glass plate, or an exposure apparatusfor producing a thin film magnetic head.

[0212] As illumination light (exposure beam) for exposure of an exposureapparatus in each of the above embodiments, it is possible to use notonly g-line (436 nm), i-line (365 nm), KrF excimer laser (248 nm), ArFexcimer laser (193 nm), F₂ laser (157 nm) and Ar₂ laser light (126 nm),but also harmonic obtained in such a manner that single wavelength laserin infrared range or visible range oscillated from DFB semiconductordevice laser or fiber laser is amplified by a fiber amplifier doped witherbium (Er) (or both erbium and ytterbium (Yb)), and the resultant iswavelength-converted into ultraviolet light using non-linear opticalcrystal. When exposure beam is used as the EUV light, reflective typeresolution is used as the master reticle. As projection optical system,it is possible to use a reflective system comprising a plurality of(about three to eight for example) reflective optical element whose oneside closer to an object is non-telecentric and one side closer to imageis telecentric.

[0213] Further, charged particle beam such as X-ray or exposure beam canbe used as the exposure beam. When the exposure beam is used forexample, it is possible to use thermionic emission type lanthanumhexaboride (LaB₆) or tantalum (Ta). The scaling of the projectionoptical system may be not only scale down magnification but also equalmagnification (1:1) or scale up magnification.

[0214] As the projection optical system, when far ultraviolet rays suchas excimer laser is used as projection optical system, far ultravioletrays-transparent material such as quartz of fluorite is used as glassmaterial, and when Ar₂ laser or X-ray is used, catadioptric system orrefractive system is used (reflective reticle is used), and whenexposure beam is used, polariscope comprising electron lens and electronoptical system is used as optical system. An optical path through whichexposure beam passes is under vacuum of course.

[0215] It is possible to produce the exposure apparatus of the aboveembodiment by incorporating an illumination optical system comprising aplurality lenses and a projection optical system into an exposureapparatus body, mounting a reticle stage and a wafer stage comprising alarge number of mechanical parts to the exposure apparatus body,connecting wires or tubes, and totally adjusting the exposure apparatusbody (adjusting electric portions, checking operations and the like). Itis preferable to produce the exposure apparatus in a clean room where atemperature and a degree of cleanness are controlled.

[0216] The exposure apparatus method of the above embodiment can also beapplied to produce other than the mask, e.g., a semiconductor device.For example, the semiconductor device is produced through a step fordesigning a function and a performance of the device, a step forproducing a reticle based on this step, a step for producing a waferfrom silicon material, a step for exposing a pattern of the reticle tothe light by the exposure apparatus of the above-described exposureapparatus (exposure method), a step for assembling the device (includingdicing step, bonding step, and packaging step), and an inspection step.

[0217] The entire disclosure of Japanese Patent Application No.10-169721 filed on Jun. 17, 1998 including specification, claims,drawings and summary and the entire disclosure of Japanese PatentApplication No. 10-290181 filed on Oct. 13, 1998 includingspecification, claims, drawings and summary, are incorporated herein byreference in their entirety.

[0218] Although various exemplary embodiments have been shown anddescribed, the invention is not limited to the embodiments shown.Therefore, the scope of the invention is intended to be limited solelyby the scope of the claims that follow.

What is claimed is:
 1. A producing method of a mask formed with atransfer pattern and to be irradiated with a predetermined exposurebeam, comprising: making design data of an original pattern obtained byenlarging said transfer pattern, applying photosensitive material intowhich a coloring matter which absorbs light in a predeterminedwavelength region is mixed onto at least one first substrate, andforming at least a portion of said original pattern on said firstsubstrate, developing said photosensitive material on said at least onefirst substrate, and with said at least one first substrate being usedas a parent mask having a mask pattern made of said photosensitivematerial remained after developing said photosensitive material,exposing a reduced image of said pattern of said parent mask onto asecond substrate while stitching said reduced image using a projectionexposure apparatus which carries out reduction projection usingillumination light in a wavelength region absorbed by saidphotosensitive material.
 2. A producing method of a mask formed with atransfer pattern, comprising: dividing said transfer pattern into anexisting pattern portion and a newly-forming pattern portion based ondesign data of said transfer pattern, forming an original patterncorresponding to a pattern of said newly-forming pattern portion onto afirst substrate to prepare a first parent mask, and with a mask formedwith another original pattern corresponding to a pattern of saidexisting pattern portion being used as a second parent mask, exposingimages of patterns of said first and second parent masks onto a secondsubstrate which is to become said mask while stitching said images.
 3. Aproducing method of a mask formed with a transfer pattern including apredetermined linear pattern, comprising: diving an enlarged pattern ofsaid transfer pattern into a plurality of parent patterns from aposition corresponding to an intermediate portion of said linear patternas a boundary portion, and projecting and exposing reduced images ofsaid plurality of parent patterns onto a substrate which is to becomesaid mask while stitching said reduced images, wherein, portions of saidplurality of parent patterns corresponding to said boundary portion ofsaid linear pattern are provided with overlapped portions each having apredetermined width in its longitudinal direction, and said overlappedportions are respectively provided with tapered portions each having awide tip end.
 4. A projection exposure method, comprising: diving apredetermined pattern into a plurality of mask patterns, and exposingimages of said plurality of mask patterns onto a substrate whilestitching screens through a projection optical system, therebytransferring an entire image of said predetermined pattern onto saidsubstrate, wherein when said predetermined pattern is divided into saidplurality of mask patterns, boundary portions of adjacent two maskpatterns are respectively provided with overlapping portions ofsuperposed portions, when an image of each mask pattern of saidplurality mask patterns is exposed onto said substrate through saidprojection optical system, said mask pattern and said substrate aremoved in synchronously with a predetermined visual field of saidprojection optical system such that the pattern of said mask patternother than said overlapping portion does not come out from saidpredetermined visual field and a pattern of said overlapping potion goesout from said visual field.
 5. A projection exposure method, comprising:diving a predetermined pattern into a plurality of mask patterns, andexposing images of said plurality of mask patterns onto a substratewhile stitching screens through a projection optical system, therebytransferring an entire image of said predetermined pattern onto saidsubstrate, wherein said predetermined pattern is divided into saidplurality of mask patterns along at least a predetermined direction,boundary portions of adjacent two mask patterns in said predetermineddirection are provided with overlapping portions of superposed portions,when an image of each mask pattern of said plurality of mask patterns isexposed onto said substrate through said projection optical system, in astate in which an image of a pattern, of said mask pattern, in a visualfield which is fixed to said projection optical system and is elongatedin said predetermined direction is exposed onto said substrate throughsaid projection optical system, said mask pattern and said substrate arescanned in synchronously with each other at the same speed ratio as aprojection magnification of said projection optical system in adirection intersecting substantially at right angles with saidpredetermined direction with respect to said visual field, and said maskpattern and said substrate are moved in synchronously with each other insaid predetermined direction in accordance with exposure time and awidth of said overlapping portion of said mask pattern with respect tosaid visual field.
 6. A projection exposure apparatus which exposes apattern formed on a mask onto a substrate through a projection opticalsystem, said projection optical system being an optical system whichexposes an image of a pattern of said mask within a predetermined visualfield onto said substrate, comprising: a mask stage capable of holdingsaid mask and moving in predetermined direction, a substrate stagecapable of holding said substrate and moving two-dimensionally includingsaid predetermined direction, and a control system which drives saidmask stage and said substrate stage to move said mask and said substratein synchronous with each other in said predetermined direction suchthat, when an entire image of the pattern of said mask is exposed ontosaid substrate through said projection optical system, a portion of thepattern of said mask does not come out from said visual field and apattern other than said portion goes out from said visual field.
 7. Aprojection exposure apparatus which exposes a pattern formed on a maskonto a substrate through a projection optical system, said projectionoptical system being an optical system which exposes an image of thepattern of said mask in a visual field which is longer in apredetermined direction, comprising: a mask stage capable of holdingsaid mask and moving in said predetermined direction and in a directionintersecting substantially at right angles with said predetermineddirection, a substrate stage capable of holding said substrate andmoving in a two-dimensional directions including said predetermineddirection, and a control system which, when an image of a pattern ofsaid mask in said visual field is exposed onto said substrate throughsaid projection optical system, drives said mask stage and saidsubstrate stage to move said mask stage and said substrate stage insynchronous with each other in a direction intersecting saidpredetermined direction substantially at right angles and to move saidmask and said substrate in said predetermined direction in synchronouswith each other such that an end of said pattern of said mask goes outfrom said visual field by a predetermined width.
 8. A producing methodof a device comprising a step for transferring a device pattern onto awork piece using a projection exposure method as recited in claim 4 . 9.A producing method of a mask as recited in claim 2 , wherein saidtransfer pattern is divided into said existing pattern portion and saidnewly-forming pattern portion by its function block.
 10. A projectionexposure method as recited in claim 4 , wherein said visual field is airradiation region of an energy beam, and an irradiation amount of saidenergy beam is gradually reduced, by said synchronous moving, in anexposure region of said overlapping portion on said substrate withrespect to a predetermined direction along which said two mask patternsare arranged.
 11. A projection exposure method, comprising the step oftransferring a mask pattern is transferred to a plurality block regionsarranged in a first direction on a substrate through a projectionoptical system to form a predetermined pattern on said substrate,peripheral portions of said block regions being partially overlapped,wherein in order to transfer said mask pattern to one block region ofsaid plurality of block regions, said mask pattern and said substrateare moved in synchronous with each other with respect to a predeterminedregion where energy beam is irradiated within a visual field of saidprojection optical system, and moving directions of said mask patternand said substrate are set to a direction which is intersecting withsaid first direction and with a second direction which intersects withsaid first direction at right angles such that an irradiating amount ofsaid energy beam is gradually reduced at said peripheral portion in saidone block region with respect to said first direction.
 12. A projectionexposure method as recited in claim 11 , wherein in order to transfer amask pattern to another block region adjacent to said one block regionon said substrate with respect to said second direction, when said maskpattern is transferred to said one block region, an irradiation amountof said energy beam is gradually reduced with respect to said seconddirection at a peripheral portion in said one block region whichpartially overlap with said another block region.
 13. A projectionexposure method as recited in claim 12 , wherein said predeterminedregion is rectangular in shape in which two sides of said predeterminedregion which are adjacent to each other respectively extend in saidfirst and second directions in a visual field of said projection opticalsystem, and a size of said predetermined region with respect to saidfirst and second directions is smaller than that of said mask pattern.14. A projection exposure method as recited in claim 11 , wherein saidmask pattern and said substrate are moved in synchronously with eachother such that a portion of said mask pattern transferred to a regionother than said peripheral portion within said block region does not goout from said predetermined region.